63 terms

Miller and Levine Biology

Chapter 7 Cell Structure and Function 7.1-7.4 vocabulary
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cells
basic units of life; unit of function and structure of all living things
cell theory
a widely accepted explanation of the relationship between cells and living things
1: all living things are made up of cells
2:Cells are the basic unit of structure and function in living things
3:New cells are produced from existing cells
how do microscopes work
most microscopes use lenses to magnify the image of an object by focusing light or electrons
light microscope
allows light to pass through a specimen and uses two lenses to form an image
staining techniques
use dyes that give off the light of a particular color when viewed under specific wavelengths of light, a property called fluorescence
objective lens
One of the movable lenses on a microscope near the specimen. There are frequently two or three objective lenses on most microscopes to enable the viewer to observe specimens at different magnification
can only be used to examine nonliving cells and tissues
ocular lens
eyepiece; remagnifies the image formed by the objective lens
light microscopes point of magnification
1000x
electron microscope
a type of microscope that uses a beam of electrons to create an image of the specimen. It is capable of much higher magnifications and has a greater resolving power than a light microscope, allowing it to see much smaller objects in finer detail
types of electron microscopes
transmission and scanning
transmission electron microscope (TEM)
make it possible to see cell structures and large protein molecules; cells and tissues have to be cut into ultrathin pieces
often appear flat or two dimensional
Scanning Electron Microscope (SEM)
pencil-like beam is scanned over the surface of the specimen; does not need to be cut
produces three-dimensional images of the specimens surface
how are cells studied with an electron microscope?
they are placed in a vacuum which keeps the cells from scattering in the air. researchers must chemically peserve the cells because of this
Light Microscope (LM)
used to study cells such as yeast or onion without seeing all of the organelles
cell membrane
A thin, flexible barrier around a cell; regulates what enters and leaves the cell
typical cell range of diameter
5-50 micrometers
mycoplasma bacteria are only .2 micrometers which can be difficult to see even under the best light micrscopess. In contasr the giant amoeba Choas choas can be 1000 micrometers
nucleus
is a large membrane-enclosed structure that contains genetic material in the form of DNA and controls many of the cells activities.
eukaryotes
cells that enclose their DNA in the nuclei, separating the genetic material from the rest of the cell
multicelllular organisms: plants, animals, and fungi
unicellular organisms: protists
prokaryotes
cells that do not separate their genetic material within a nucleus
bacterias which respduce, respond to their enviromet, and glide along surfaces or swim through liquids
cytoplasm
is the portion of the outside of the nucleus; A jellylike fluid inside the cell in which the organelles are suspended
organelles
Structures specialized to perform distinct processes within a cell.
nucleus
contains nearly all of the cells DNA and coded instructions for making proteins and other important molecules
nuclear envelope
dotted with thousands of nuclear pores which allow material to move into and out of the nucleus
chromatin
complex of DNA bound proteins which carry the cells genetic information; chromosomes found in the nucleus
nucleolus
a small dense region in the nucleus where the assembly of ribosomes begin
vacuoles
large saclike, membrane-enclosed structures which is filled with liquid. Mostly found in plants and increased the cells rigidity , making it possible for plants to hold heavy structures such as leaves and flowers. Some are also found in unicellular organisms and some animals.
contractible vacuole
specialized vacuole pumps excess water out of the cell and move materials between cell organelles as well to the cells surface
lysosomes
small organelles that break down lipids, carbohydrates, and proteins into small molecules. They are also involved in breaking down dead organelles.
cytoskeleton
a network of protein filaments that give shape and internal organization to the cell. Helps maintain its shape and also is involved in movement.
microfilaments
threadlike structures made up of a protien called actin. Produces a tough flexible framework that supports the cell.
microtubules
hollow structures made up of proteins called tubulins. Play a critical role in maintaining cell shape, cell division forming a structure called miotic spindle which helps seperate chromosomes. In animal cells they can form centrioles. They also help build projections for the cell surface: cilia (plural: cilium) and flagella (plural: flagellum) which allow the cells to swim rapidly through liquid.
centrioles
located near the nucleus and help organize cell division. Are not found in plant cells
what structure are cilia and flagella arranged in?
a 9 by 2 arrangement making small cross bridges between microtubules in the organelles that use chemical energy to pull or slide along the microtubules producing controlled movements.
what organelles help make proteins ?
proteins are made on the rough ER which will be released or secreted, from the cell as well as many membrane proteins and proteins destined for lysosomes and other specialized loactions within the cell.
What organelles help transport proteins?
appears as a stack of flattened membranes. Modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or release outside of the cell
golgi apparatus
Modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or release outside of the cell
ribosomes
small particles of RNA and protein found throughout the cytoplasm in all cells and on the rough endoplasmic reticulum. ribosomes produce proteins by following coded instructions that come from DNA.
When are cells especially active?
in protein synthesis often containing large numbers of ribosomes
endoplamsic reticulum
a structure which eukaryotic cells have which lipid components of the cell membrane are assembled along with proteins and other materials that are exported throughout the cell
smooth endoplasmic reticulum
ribosomes are not found on the surface, but contains enzymes that peform specialized tasks including the synthesis of membranes and the detoxification of drugs.
Liver cells which play a key role in detoxifying drugs often contain large amounts of smooth ER.
rough endoplasmic reticulum
portion of the ER which is involved in protein synthesis. Newly made proteins leave these ribosomes and are inserted into the rough ER where they may be chemically modified .
chloroplasts
capture the energy from the sunlight and covert it into food that contains chemical energy in a process called photosynthesis.Surrounded by two membranes and inside are large stacks of other membranes, which contain the green pigment chlorophyll.
Mitochondria
converts the chemical energy stored in food into compounds that are more convenient for the cell to use. Two membranes and an inner membrane that is folded up inside enclose it. Contains its own genetic information in the form of small DNA molecules
cell wall
produces a strong supportive layer around the membrane which helps maintain shape and protect the cell. Animal cells do not have cell walls but prokaryotes and plan cells do. These walls lie outside the cell membrane
what does it mean when a cell is porous enough?
allowing materials such as water, oxygen, carbon dioxide, and other substances to pass through easily
why do plant cells need cell walls?
the cell walls give the plants strength needed for plants to stand against the forces of gravity. In trees and larger plants nearly all of the tissue of the wood is made up of cell walls.
cell membrane
regulates what enters and leaves the cell and also protects and supports the cell
lipid bilayer
gives cell membrane a flexible structure that forms a strong barrier between the cell and its surroundings. Created when lipids including phospholipids that are common in animal cells, are mixed with water. These hydrophobic fatty acid tails cluster together while the hydrophillic heads are attracted to water. Hydrophillic heads of the lipids face towards the outside of the cell whereas the hydrophobic tails face towards the inside of the oily part of the membrane which keeps water out
properties of lipids
have oily fatty acid chains attached to chemical groups that react strongly with water. The fatty acid portions of lipids are hydrophobic meaning that they attract form water
hydrophobic
"water hating", or in other terms propels from water

phobic=phobia- fear/ propolsion
hydropillic
"water loving", or in other terms attracts water

phillic=full- full of water
The fluid mosaic model
because the proteins embedded in the lipid bilayer can move around and float amoung the lipids and so because many different kinds of molecules make up the celll membrane scientist decribe the celll membrane as a "fluid mosaic".
what do proteins form in order to help material across the cell membrane?
channels and pumps
why do some proteins attach directly to the cytoskeleton?
This allows cells to respond to their enviroment by using their membranes to help move or change shape.
what does it mean when a membrane is selctively permable?
that the membrane allows some substances to pass through and some cannot.
*are also called semipermable membranes
what controls the cellular center?
the nucleus
what organelles store, clean-up, and support the cell?
vacuoles and vesicles, lysosomes, cytoskeleton, and centrioles
what organelles build proteins?
ribosomes, endoplasmic reticulum, and the golgi apparatus
What organelles capture and release energy?
the chloroplasts and mitochondria
what organelles are the cellular boundries?
the cell wall and the cell membrane
diffusion
the process in which the molecules of a substance move from an area of higher concentration to an area of lower concentration. Doesn"t require cell energl, but is the driving force of the movement of many substances across the cell membrane.
1:there is a higher concentration of solute on one side of the membrane than on the other
2: diffusion causes a net movement of solute particles from the side of the membrane with the higher solute concentration to the side with the lower solute concentration.
3: Once the equillibrium is reached solute particles continue to diffuse across the membrane in both directions but at approximately equal rates, so that there is no net change in solute concentration
passive transport
the movement of materials across the cell membrane without using cellular energy
facilitated diffusion
the process in which molecules that cannot directly pass through use special protein channels without requiring any cellular energy.

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