lenses nearest the eye through which you look; 10x
lenses of different magnification that work in comjunction with ocular lenses to magnify the image; 40x
housing that keeps ocular and objective lenses in proper alignment
revolving housing that supports objective lenses
supports microscope body, stage, and adjustment knobs
moves stage up or down to focus image
permits precise focusing
hold slide in steady, stationary position
stage adjustment knobs
move stage to center slide under objective lens
lens mounted beneath stage that foucses light beam on the specimen
mounted beneath stage nere condenser; regulates amount of light illuminating specimen
moves condenser lens up or down to focus light
source of light
supports microscope unitlight intensity adjustment dial
light intesity adjustment dial
rheostat (dimmer switch) that permits further adjustment of light intensity
turns microscope light on or off
between objective lens and the slide
What does the letter "e" look like through the ocular lenses?
upside down and backwards
As you move the slide toward the right of the stage, to which direction does the image of the "e" move when viewed through the microscope?
As you move the slide away from you on the stage, to which direction does the image move?
towards you (opposite)
distance between the objective lens and the slide
oil immersion lens
field of view
the circular field that you see when looking through a microscope
Under which objective lens is the field of view largest?
Under which objective lens is the field of view smallest?
If you didn't know what you wre looking at already, could you still determine if it was an "e" using high-power alone?
No, because the field of view would be to small.
Which lens (low-,medium-,or high-power) gives you the largest working distance?
depth of field
the thickness of an image that is in focus at any poin in time
technique that allows you to observe movements and properties of living specimens that are impossible to view with prepared slides
Making a wet mount step 1
place specimen on clean glass slide
Making a wet mount step 2
place a drop of pond water culture in the center of a clean glass slide
Making a wet mount step 3
add a coverslip by placing one edge along the drop and gently lowering it onto slide
Making a wet mount step 4
press gently on the coverslip to remove any tiny air bubbles
Which level of magnification requires the most illumination for the best clarity and contrast?
Why is it imperative that you place a coverslip over the drop of fluid when making a wet mount?
so the fluid doesn't spread and leak of the slide
much larger working distance than compound micro.& are designend for viewing whole specimenst that are too large, too thick, or to opaque for study; ocular lens vies the specimen at a slightly different angle through the objective lenses, providing a three-dimensional view of the specimen, with a large depth of field; magnification 4x to 50x
light from above
light from below; perferable for viewing internal structures on extremely thin or transparent specimens
What is the magnification range of the stereoscopic microscope?
4x to 50x
How does the image through a stereoscopic microscope move when the specimen is moved to the right or left? Up or down?
moving an object in agiven direction on the stage the image moves in same direction
For thin, transparent specimens, which method of illumination is genereally better-- transmitted or reflected light?
Which method is better for larger thicker specimens? transmitted or reflected light
Use lower/smaller or higher/larger to filll in the blanks...When compared to most compound microscopes, stereoscopic microscopes have a___ working distance,___depth of field,___ field of view, ___magnification, and___resolution.
larger, larger,larger, lower, lower
Basic Dissection Techniques
(1)practice safe hygiene--appropriate gloves, clothing, eyewear, don't put hands near mouth or eyes
(2) Read all instructions carefully before making any incisions--make sure you understand directions
(3) Use scissors, a teasing needle, & blunt dissecting probe whenever possible--scalpels more harm than good
(4) Don't stick your scalpel or teasing needles into roubber wax bottoms of disecting pan
(5) When instructed "expose" or "view" an organ remove all the membranous tissues that typpically cover these organs (fat, fascia, ect.) and separate--goal to expose the organ or structure as completely as possible without causing damage
(6) Working in pairs--one reads while other disects
(7) Look at illustrations frequently but primarily focus on specimen
Purpose of Disection
to reveal organs and structures in their natural, intact state for observation, without cutting or destroying them
lack a symmetry; irregular arrangement of body parts with no plane of symmetry to divide them into similar halves; ex. sponges
arrangement of body parts around a central axis; any plane passing through the central halves (mirror images) by a single plane of symmetry; ex. cnidarians, some adult echinoderms, some sponges.....star fish
division of body parts into similar halves (mirror images) by a single plane of symmetry; ex. flatworms, segmented worms, molluscs, arthropods, larval echindoerms, chordates
a section perependicular to the long axis of the body separating the animal into anterior and posterior
longitudinal section separating the animal into right and left sides;
runs down midline of animal
structures that are closer to the median plane
structures that are farther from the median plane
longitudial section dividing the animal into dorsal and ventral parts
denotes the side of the body nearer the backbone
refers to the side of the body closer to the belly
refers to a point of reference nearer the median plane or point of attachment on the body than another structure; ex when your arm is exteded, your elbow is proximal to your hand
refers to a point of reference farther from the body's median plane or point of attachment than another structure; ex. when your arm is exteded, your elbow is distal to your shoulder
refers to a point closer to the tip of the nose
(1)all organisms are composed of cells
(2)cells are basic living units of organization and function in all organismis
(3)all cells arise only by division of previously existing cells
a specialized, usually spherical mass of protoplasm encased in a double membrane, and found in most living eukaryotic cells, directing their growth, metabolism, and reproduction, and functioning in the transmission of genic characters.
peripheral cytoplasm surrounds the nucleus; the cell substance between the cell membrane and the nucleus, containing the cytosol, organelles, cytoskeleton, and various particles.
darker, surrounding cytoplasm, thin outer boundary of a cell that regulates the traffic of chemicals between the cell and its surroundings
darkly-stained clups within the nucleus;; the readily stainable substance of a cell nucleus, consisting DNA, RNA, and various proteins, that forms chromosomes during cell division.
small spherical structure; a conspicuous, rounded body within the nucleus of a cell
The Four Principal Tyeps of Animal Tissues Based on Structure And Type
Epithelial tissues definition
cover external surfaces for protection or line the internal surfaces of body
protect or line internal surfaces of body cavities and vessels; typically arranged into tightly packed layers of cells with little or no intercellular space; categorized based on the shapes of the cells and the number layers of cells that constitue the tissue;
Simple Epithelial tissues
consist of a single layer of cells and are classified based on their shapes; typically tww-deminsonal appereance in microscope; viewed from the side, often are difficult to distinguish; a thin band of cytoplasm with a small bulge wher the nucleus apperas is usually all that is identifiable
Simple Squamous Epithelium
A single layer of thin, flat cells. It is often found where diffusion or filtration take place (alveoli in lungs, kidneys). It also covers organs in the pericardial, pleural, and peritoneal cavities.
Cuboidal Epithelium and Columanr Epithelium
contain cells that are thicker and fuller and have three-deminsional apperances
Simple Cuboidal Epithelium
represented by a single layer of boxed shaped cells; found in tubules of the mammalian kidney, & simple columnar cells are prevalent in the inner lining of the intestines in mammals
Simple Columnar Epithelium
contains a single layer of elongated, rectangular cells
Epithelial tissues typically exist in simple layers when absorption or diffusion across the tissues is necessary.
name from layered arrangment of cells in the tissues; many cases, theses tissues are composed of more than one type of cell ex.=severeal layers of squamous cells follwed by severeal layers of cuboidal cells
Epithelial tissues typically exist in stratified layers to serve as barriers against foreign substances and injury.
For example, the skin consists of an outer layer of stratified squamous epithelium to protect against impact, abrasion, radiation, desiccation, and infection
Stratified Squamous Epithelium
Function: protects underlying tissues in areas subjects to abrasion *** Location: esophagus
bind, support, store nutrients, and protect body parts and system
Connective tissue Categories
tendons, artilage, fat, blood and bone
All Connective tissues have a common structural feature called
contains cells that are widley-spaced by an extracellular matrix secreted by the living cells
crystals that make the bone hard; in blood, the extracellular matrix is plasma; in cartilage the extracellular matrix is composed of
most common connective tissue in vertebrates; composed widley-spaced cells within agleatinous glycoprotein matrix that provides firm but flexible support
hollow chambers****Location:emedded within the matrix
cartilage producing cells****Location:in the lacunae
Location between bones, where it cushions the surfaces, of jouints; intercellular matrix composed primarily of chondrin with thin collagen fibers to provide support and suppleness
contains fine collagen fibers and many ejlastic fibers that provide greater elasticity to this cartilage; more flexible than hyaline cartilage; *****Locations:ear nose and voice box of humans
one of the most specialized structural connective tissues; provides structural support; stores calcium that can be withdrawn by the body as blood calcium levels drop; produce red blood cells in the bone marrow
bone producing cells
concentric layers of bony connective tissue
tiny, narrow pathways
small spaces between the lamellae which contain osteocytes
timy, fingerlike projections through which nutrients is transported to the osteocytes
is a type of connective tissue that stores or sequesters food for the body in the form of fat droplets
Loose Connective tissue
found in all vertebrates; , A loosely organized, easily distorted connective tissue that contains several fiber types, a varied population of cells, and a viscous ground substance. Also the packing materials of the body. Fill spaces between organs, cushion and stabilize specialized cells and support epithelia. Surround and support blood vessels and nerves, store lipids, provide route for the diffustion of materials
a fibrous scleroprotein in bone and cartilage and tendon and other connective tissue
cells that secrete collagen and other fibrous proteins
Dense Connective Tissue
contains tightly packed collagen fibers, making it stronger than loose connetive tissue; classified based on the arrangement of collagen fibers into regular and irregular types
Regular Dense Connective Tissue
extremely long, densely packed, and are arranged in parallel, like the strands of a rope, forming s tructures that are extremely resistant to stress; ex. tendons, ligaments
Irregular Dense Connective tissue
lack a parallel arrangement; fibers have many different orientation patters, often arranged in bundles distributed in all directions thorughout the tissue, as in the dermis of the skin; produces tough outer coverings of organs such as kidneys, muscles, and nerves help hold them together
classifed as a type of connetive tissue; fluid nature
in which cells and the fluid matrix are suspended course through blood vessels transporting oxygen, carbon dioxide, nutrients, electrolytes, hormones, metabolic watses and practically any other substance that cells use or produce
produced by liver; helps blood clot; plasma contains this
produced by liver; exerts an osmotic force needed for fluid balance; plasma contains this
produced by lymphocytes; needed for immunity; plasma contains this
not floating freely in the plasma of vertebrates, its tightly packaged within the red blood cells; floating freely in invertebrates;
free-floating respiratory pigment in plasma; found in annelids
free-floating respiratory pigment in plasma; found in molluscs and arthropods
mammalian red blood cells; appear as tiny, light pink, biconcave discs; most numerous type of cell in blood; 4-5 billion per mililiter of blood in adult humans; contain hemoglobin to reversibly bind and transport oxygen and carbon dioxide; characteristic biconcave shape provides a highter surface-to-volume ratio; increasing the diffusion rates of oxygen and carbon dioxide into and out of the cells
white blood cells; genrerally larger than erythrocytes and contain distinct, purplish nuclei; play roles in defending the body against invading microorganisms and other foreign substances
most abundant white blood cell; twice the size of a red blood cell; ***Function: Bacterial Phagocytosis; the principal phagocytic cells in blood and are specialized for seeking out and ingesting foreign bacterialcells and dead host cells
least common; twice the size of red blood cells; ***Function: Inflammatory and Allergic Response; typically have unlobed nuclei; mor granular apperance when stained; instrumental in the inflammatory response of allergic reactions and help to prevent blood from inappropriately cloting within blood vessels
***Function: Allergic Response and Parasite Defense; play a role in allergic response; help defend against parasites; twice the size of red blood cells; nuclei usually possess two lobes
slightly larger than red blood cells; ***Function: Produce Antibodies For Immune Response; have spherical nuclei that almost completely fill the interior of the cell, leaving little visible cytoplasm; produce antibodies that recgonize and destroy foreign cells
the largest of the white blood cells; ***Function: Phagocytosis; spend a brief time (1-3 days) developing in the blood before exiting circulation and completing their developemnt in the tissue
monocytes greatly enalrge and become macrophages; giant scavenger cells that voraciously engulf bacteria, dead cells, and other debris
tiny, disk-shaped bodies in the blood, important in blood clot formation
Which type of connective tissues provides the most rigid support?
Which type of connective tissue stores lipids?
Tendons and ligaments are composed of ______
regular dense connective tissue
Are nuclei present in mammalian red blood cells?
No, they lack a nuclei
WHich general type of blood cell is the most numerous? the least numerous?
most numerous = erythrocyte
least numerous = leukocyte
Name five categories of types of leukocyte
Which type of leukocyte is the most numerous? the least numerous?
most numerous = neutrophils
least numerous = basophils
What general strutural features do all connective tissues share in common?
permit movement of the animal through its environment and/or movement of substances through the animal; characteristics ability to contract and thus create movement
Actin and Myosin Filaments
these occur in abundance and in uniform orientation in muscle cells; responsible for the contractility of muscle tissues
Types of Muscle Tissues
(1) SMOOTH MUSCLE
(2) SKELETAL MUSCLE
(3) CARDIAC MUSCLE
simplest type of muscle tissue; lacking striations and generally confined to regions of the body under autonomic nervous control; long and spindle shaped fibers; contain nuclei; found in: bladder, uterus; stomach; blood vessels; contractions slow and rhythmic
composed of long, unbranched myofibrils that are actually composites of many individual muscle cells, giveing these fibers their multinucleated apperance, a muscle that is connected at either or both ends to a bone and so move parts of the skeleton; characteristics: striated apperance
Micorsopic, fiber-like structures that occupy most cytoplasm in skeletal muscle cells: , skeletal muscle fibers
protein filaments inside a myofibril are organized into repeating functional units
strained muscle is found in the walls of the heart; not voluntary control; nuclei not located on the periphery of the cells; has steady rhythmic contractions; composed of bands of muscle fibers
groups of nerve cell bodies that coordinate incoming and outgoing nerve signals; control the rhythmic contractons; embedded in the heart
Attachment sites between the transverse lines between cardiac muscle cells; rings that provide a strong connection between cardiac muscle cells, to prevent tears and leaks in the heart.
initiate and transmit electrical nerve impulses to and from the body parts and store information in the form of biochemical compounds
Nervous Tissues Major Cells
(2) GILIA CELLS-supporting cells
Neurons are made up of_____ and are located
(1) CELL BODY
located in the brain and spinal cord ONLY!!!
contains the nucleus and other organelles
long; transmits electrical impulses away from the cell body
short extensions; typically recieve electrical impules from neighboring neurons or sensory receptors and transmit them to the cell body
assist in propagating nerve impulses; provided a nuritive role for neruons
proteinaceous substance that coats axons nerve cells seaths
cell division in which the nucleus divides into nuclei containing the same number of chromosomes
reproduction that does not involve the union of gametes and in which a single parent produces offspring that are genetically identical to the parent
the cycle of growth and asexual reproduction of a cell, consisting of interphase (g1, s, g2 cycles) and mytotic phase (mytosis[division of the cell in prophase, prometaphase, metaphase, anaphase, and telophase cycles] & cytokinesis[splitting of the cell])
stage of interphase in which cell grows and performs its normal functions
The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.
stage of interphase in which cell duplicates its cytosol and organelles
division of cytoplasm, in which the cell membrane pinches apart forming two physically separate cells
growth, reproduction, and division
first (if not counting interphase), during which the chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus
identical copies of a chromosome; full sets of these are created during the S(DNA replication) subphase of interphase
area where the chromatids of a chromosome are attached
two tiny structures located in the cytoplasm near the nuclear envelope
protein structures which move the chromosomes during cell division.
alignment of chromosomes
a site of attachment at the chromosome's centromere
The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell. (third stage if not counting interpahse)
single-stranded chromosomes complete their migration toward opposite poles of the cell; events of prophase are reversed
organic process consisting of the division of the cytoplasm of a cell following karyokinesis bringing about the separation into two daughter cells
the area of a cell membrane that pinches inward during animal cell mitosis eventually dividing the cell
If a cell has 20chromosomes during G1 of interphase, how many chromosomes would be present during prophase?
How may chromosomes would each of the two new cells have that resulted from the mitoic division of this cell?
Which stage takes the shortest time to complete?
The process that occurs in the formation of sex cells (sperm and egg) by which the number of chromosomes is reduced by half.
n = 23 (single set); have half the number of chromosomes as the somatic cell
Differences Between Meiosis And Mitosis
(1) Meiosis involves two successive nuclear and cytoplasmic divisions, generally producing four daughter cells
(2) Despite two successive nuclear divisions, the DNA and other chromosomal components are duplicated only once, during interphase preceding the first meitoic division.
(3) Each of the four cells producedc by meiosis contains the haploid chromjosome number of the parent cell.
(4) During meiosis, the genetic information form homologous chromosomes is shuffled, so each resulting haploid cell has a potentially unique combination of genes.
Meiosis generally consists of 2 successive nuclear divisions known as_______ and ________
meiosis I and meiosis II
the first phase of meiosis where homolygous chromsomes are separated, and the cells split in half
the second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting in two
first phase of meiosis I; the homologous pairs of double-stranded chromosomes actually join together called SYNAPSIS, forming tetrads
the paired chromosomes consisting of four chromatids
second pahse of meiosis I; Spindle fibers attach to the chromosomes. The chromosomes then line up across the center of the cell.
the exchange of genetic material between homologous chromosomes
The third phase of meiosis I. During anaphase I the replicated homologous chromosomes are separated (the tetrad is split) and pulled to opposite sides of the cell.
During meiosis II:
double-stranded chromosomes in each daughter cell divide again separating into single-stranded chromosomes that move to opposite poles, producing 4 haploid daughter cells, each with half the number lof the single-stranded chromosomes as the original cell
How does meiosis create genetic diversity for natural selection to opereate?
the genetic infromation from homologous chromosomes is shuffled, so each resulting haploid cell has a potentially unique combination of genes
Do tetrads form during mitosis?
NO, they form during meiosis in prohphase I
production of gametes through meiosis
Male gametogenesis; the meiotic production of sperm cells, occurs within the tiny coiled seminiferous tubuels of the testes
The diploid cells in a testis that can give rise to primary spermatocytes.
produced from spermatogonium cell and undergoes meiosis to produce two secondary spermatocytes
Haploid cells resulting from the first meiotic division of spermatogenesis. Secondary spermatocytes are ready to enter meiosis II.
haploid, 23c, spermiogenisis, form from secondary spermocytes and form 4 spermatozoons or sperm cells
Mature sperm specialized for transporting the genetic information from the male to the ovum. continue to produce throughout males life=cheap
meiotic production of eggs (or ova)
female stem cells found in a developing fetus. Oogonia no longer exist by the time of birth
immature egg cells; remain arrested in prophase I of meosis until the appropriate hormonal cues cause themto reusme division....may remain there for up to 50years
A haploid cell resulting from the first meiotic division of oogenesi (not that the cytoplasmic division in this case is unequal, producing one large cell with almost all of they cytoplasm - the secondary oocyte- and one smaller cell with virtually no cytoplasm - the first polar body.). The secondary oocyte (along with some follicular cells) is released from the ovary during ovulation.
a small cell containing little cytoplasm that is produced along with the oocyte and later discarded
secondary oocyte splits into a polar body & ovum
Females produce 400,00 eggs at birth but only a few hundred of these cells will ever mature into ova and be releasend into the oviducts; eggs=not cheap; limited supply
In spermatognium has 20 chromosomes, how many chromosomes will be present in a mature sperm cell from that spermatogonium?
How many sperm cells will one spermatogonium produce?
If an oogonium has 20 chromosomes, how many whromosomes will be presentin an ovum from that oogonium?
How many ova will one oognium produce
400,000 & only a few hundred will mature
Describe how the production of nonfuctional polar bodies is adaptive for the resulting ovum.
it disnigtegrates, leaving only a large ovum well stocked with enough nutrients and reserves to make it through the first few divisions after fertilization
eukaryotic one-celled living organisms distinct from multicellular plants and animals: protozoa, slime molds, and eukaryotic algae
multicellular; ex. algae
A cell characterized by the presence of a nucleus and other membrane-bound organelles. Eukaryotes can be unicellular (protists) or multicellular (fungi, plants and animals).
self-nourishing; pertaining to the ability of an organism to produce its own nutrients from inorganic compounds
requiring organic compounds of carbon and nitrogen for nourishment; ex most animals are; and some plants
darker, surrounding cytoplasm, thin outer boundary of a cell that regulates the traffic of chemicals between the cell and its surroundings
rigid structure that encloses, supports, and protects the cells of plants, algae, fungi, and most bacteria
plants store their reserves of glucose as this;, Plant carbohydrates
energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen
dormant larvae surrounded by protective coverings;, formed by protists to temporarily protect them from harsh environments (heat, dessication, salt, adic, etc)
Pertaining to a taxon derived from a single ancestral species that gave rise to no species in any other taxa.
pertaining to a group of taxa derived from two or more different ancestors (protists(protista))
flagellated unicellular; primarily live in fresh water. have characteristics of plants and animals. have flagella to propel them through the water.
monophyletic proposed kingdom of Euglenozoa; unicellular; parasitic flagellates
all are unicellular; motile flagellates; reproduce asexually by Binary Fission; many heterotrophic but some are also photosynthetic; flexible cell membranes
Euglenoids Example: Euglena
Euglena: a complex unicellular organism with many vissible organelles
Characteristics Of Euglenoids:
anterior pocket that bears one or two flagella extedning from the reservoir in the anterior end of the organism; near the base of the primary flagellum is a pigmented eyespot (serves as a photoreceptor providing chemical info. to the cell about the ntesity of light in its environ.); a large central nucleus and many large chloroplasts;
organelles that capture the energy from sunlight and convert it into chemical energy in a process called photosynthesis
accessory photosynthetic pigment
one or more spherical organelles that pump water out to maintain the internal osmotic balance of the cell
What color is the photoreceptive eyespot of Euglena?
How might such an eyespot be advantageous for an autotrophic organism?
Serves as a phtoreceptor, providing chemical info. tp the cell about the intesity of light in the environment
In what ways might Euglena be considered plant-like?
autotrophic--they make their own food; sedentary
In what ways might Euglena be considered animal-like?
motile; heterotropic ingest large food--digest then intracellulary
Kineotplastids Example Trypanosoma
Characteristics Of Kinetoplastids
single, large mitochondrion containing a kinetoplast
unique organelle that houses extra-nuclear DNA
causes African Sleeping Sickenss/spread by a bite of the tsetse fly
a lash-like appendage used for locomotion (e.g., in sperm cells and some bacteria and protozoa)
extends beyond one end of the body
Describe the length and width of a trypanosome compared to a red blood cell.
its skinnier and longer
Are trypanosomes larger or smaller than Euglena?
Do trypanosomes possess chloroplasts? How do they obtain nutrients?
NO, they have kinetoplast; they get it from the host's blood
How are kinetoplatid similar to euglenoids
unicellular, motile flagelletas that reproduce asexually by binary fission
A protistan clade that includes dinoflagellates, apicomplexans, and the ciliates. Alveolates have small membrane-bounded cavities called alveoli under their cell surfaces. The function of alveoli is unknown.
small cavities under the cell's surfaces
Alveolata Examples: Dinoflagellates, Sporozoans, Ciliates
nonmotile; highly specialized for their parasitic lifestyle;, a form of protozoa; eukaryotic microorganism
non-motile; characterized by an apical complex of organelles that they use to penetrate the host cell
Do sporozoans (such as plasmodium) possess organelles for locomotion?
NO, they are all non-motile
Does every red blood cell contain a parasite?
Can you detect different stagews of infection on the same slide?
a group of protozoans that move by waving tiny, hair-like organelles called cilia; most live in freshwater; but their specific arrangements of cilia allow ciliates to be specialized for different lifestyles
class of protozoa having cilia or hairlike appendages on part or all of the surface during some part of the life cycle
Two types of nuclei
completely covered by cilia
cilia are clustered into few rows along the body
form of sexual reproduction in which paramecium and some prokaryotes exchange genetic information
stiff outer covering that maintains basic cellular shape
hair-like projections used for locomotion and feeding
organelle containg many copies of a few genes; primarily controls metabolic processes of cell
typically eukaryotic nucleus containing entire genome; essential for genetic recombination
lateral depression into which food swept by ciliary currents
tubular invagination lined with cilia where food enteres and food vacuoles form
small, spherical organelle containg enqymes to digest food
one or more spherical organelles that pump water out to maintain the internal osmotic balance of the cell
anal spot (cytoproct)
site where indigestible matter is expelled from the cell
a form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size
Do the cilia of Paramecium beat in unison or in small groups?
Is the plane of division during fission along the longitudinal or transverse axis?
Why is conjugation considred a form of sexual reproduction?
Because the micronucleus divides into 2 haploid cells (female, male) and these 2 cells make 2 new cells
Recurrent Body Forms (Amoebas)
unicellualr heterotrophs that lack cell walls; specialized protists; creeping motion and manner to engulf food particles; lack the ability to reproduce sexually; majority are free-living; some are parasitic (Entamobea histolytica cause of amoebic dysentery in humanns (through contaminated sources of drinking water and food)
cytoplasmic extensions that are used for feeding and locomotion
amoebas engulf their food by this process in which extentinsions of the plasma membrane (pseudopodia) elongate and surround the food item.
b/w 5,000 to 10,000 species of sponges make up this phylum; , sponges; sessile animals that lack true tissues; suspension feeders, trap particles that pass through the interal channels of their bodies
All sponges share these anatomical similarites:
(1) All sponges are sedentary animals that have no body symmetry and lack tissues, organs, or organ systems. As a result, all major biological functions occur at the cellular level.
sedentary--remain in one place
(2) Their simple bodies consist of juts four primary cell types arranged around a system of pores and canals.
(3) All sponges feed by filtration---their collar cells create water currents thatpull in organic particles.
(4) Sponges have an internal meshwork of microscopic spicuels or collagen fibers, which serves as an internal skeleton.
feeding cells (AKA collar cells); joint action of choanocyte flagella moves water through the sponge; delivers food, oxygen, gametes; carries off wastes (mostly ammonia)
free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals.
Sponge Body Types
has no folding and simply a hollow tube; size:small surface-to-volume ratio; simplest and least common sponge body,
folded wall sponge; increased surrface-to-volume ration; allows sponges to be larger
most common (majority) sponge; complex--body folds that are themselves folded, resulting in a series of chambers connect by canals; ex bath sponges
central part of the water canal system
water enteres the sponge through these pores on the body
ostia channels water down these______canals to a larger number of tiny pores scattered along the folds of the incurrent canals
the tiny pores scattered along the folds of the incurrent canals are actually openings in elongated, doughnut-shaped cells
porocytes channel water into flagellated chambers known as the ______canals.
are mobile cells that reside in the gelatinous matrix b/w the choanocytes and the pinacocytes; carry food to other cells within the sponge body; they can undergo developmental changes to transform into any other cell type that may be required for the sponge to function properly
cells making up the outer layer of the sponge
pore between radial canal and spongocoel; the large opening in which H2O, now devoid of dissolved oxygen and food particles, pass out of each radial canal
located at the top of the sponge; an opening in a sponge's body through which water exits
another form of asexual reproduction seen in sponges; common in freshwater sponges; rare in marine species; densely-matted, hardended ball containing amoebocytes surrounded by a coating of collagen and spicules;
Gemmules Response to Environmental Conditions:
the sponge body may disintegrate, leaving the gemmuels behind; thes progected balls can survive through the winter and then form a new adult sponge in the spring
Sponges occasionally reproduce sexually when_____
envrionmental conditions are favorable; sponge divides meiotically to become haploid sperm, then are released into water; sperm cells entr a different sponge body; they are captured and transferred into cells that travel through embedded haploid egg; fertilized egg then develops into simple ciliated larva
For each of the sponge cell types listed below define the function....
(1) makes up the outer layer of a sponge
(2) carries food to other cells; reside in gel
(3) channels H2O into flagellated chambers
(4) trap food particles
List the three types of sponge body plans from leas complex to most comples
ascon, sycon, leucon
Water flows into the sponge body through numerous poeres on the outer surface called_______, and then along incurrent cannals passing through other smaller openings in specialized cells called______, into ______canals that are lined with choanocytes. Finally, the water dumps into the_______, the large central chamber in most sponges, and is released from the sponge body through the______.
ostia, porocytes, radial canals, spongocoel, osculum
True or False? Sponges have the ability to reproduce sexually and asexually.
are the skeletal elements of sponges ane are secret by amoebocytes---mobile cells cspeicailized for distributing food throughout the sponge and for producing its skeleton.
Many sponge skeleton are composed of hard, crystalline, spicules formed from either calcium carbonate or silicon.
example bath sponge; more flexible; proteinaceous material
Freshwater Sponges Role in the Environment:
important ecological role; they create "micro-currents" in the water surrounding sponges which keeps the water from becoming stagnant and contributes to the naturalfiltration process of lakes and ponds
play an important role in freshwater ecyosstems as well, because sponges keep water moving "new" water into their immediat vincinty and pushing away "old", oxygen-depleted water