Anatomy & Physiology Chapter 3

Cell Structures and Their Functions
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Terms in this set (...)

Cell
Basic living units of all organisms
Light Microscope(s)
Allows us to visualize the general features of a cell
Electron Microscope(s)
Used to study the fine structures of a cell

Higher magnification than an light microscope
Scanning Electron Microscope(s)
Microscope that allows us to see the features of a cell's surface as well as the surfaces of internal structures
Transmission Electron Microscope(s)
Microscope that allows us to see "through" parts of a cell to help determine cell structure
Plasma Membrane
Forms the outer boundary of a cell

Also called the cell membrane
Organelle(s)
Specialized structures within a cell that perform specific functions
Nucleus
Contains the genetic material of a cell

Directs cell activity

Centrally located
Cytoplasm
Located between the nucleus and the plasma membrane

Contains many organelles
Structure and Function
The number and type of organelles within each cell type determines the cells specific _____ and _____
Cell Metabolism
The chemical reactions that occur within cells are referred to collectively as?
Heat
This by-product produced during cell metabolism helps to maintain body temperature
Communicate
Cells produce and receive chemical and electrical signals which allow them to?
Gamete(s)
Specialized cells of the body responsible for transmitting genetic information to the next generation
Main Functions of a Cell
Cell metabolism and energy use
Synthesis of molecules
Communication
Reproduction and inheritance
Intracellular Substance(s)
Substances inside of the cell
Extracellular Substance(s)
Substances outside of the cell
Intercellular
Another name for extracellular substances

Meaning "between cells"
Phospholipid(s)
Cholesterol
Predominant lipids of the plasma membrane
Lipid Bilayer
Double layer of phospholipid molecules

Forms a barrier between the inside and outside of the cell
Hydrophilic
Polar, phosphate-containing ends ("heads) of the phospholipid bilayer
Hydrophobic
Nonpolar, fatty acid ends ("tails") of the phospholipid bilayer
Fluid-Mosaic Model
Modern concept of the plasma membrane suggesting it is highly flexible and can change its shape and composition through time
Marker Molecules
Cell surface molecules that allow cells to identify one another or other molecules

Allow immune cells to distinguish between self-cells and foreign cells
Glycoprotein(s)
Proteins with attached carbohydrates
Glycolipid(s)
Lipids with attached carbohydrates
Attachment Protein(s)
Allow cells to attach to other cells or to extracellular molecules

Can also attach to intracellular molecules
Cadherin(s)
Proteins that attach cells to other cells
Integrin(s)
Proteins that attach cells to extracellular molecules

Also function in cellular communication
Transport Protein(s)
Extend from one surface of the plasma membrane to the other and move ions or molecules across the plasma membrane

Include: Channel Proteins, Carrier Proteins, ATP-Powered Pumps
Membrane Channel(s)
Channel proteins form these, which are like small pores extending from one surface of the plasma membrane to the other
Receptor Protein(s)
Proteins or glycoproteins in the plasma membrane with an exposed receptor site on the outer cell surface which can attach to specific chemical signals
Enzymes
Protein catalysts which increase the rate of chemical reactions on either the inner or outer surface of the plasma membrane
Selectively Permeable
Plasma membranes are this... allowing some substances, but not others, to pass into or out of a cell
Enzymes
Glycogen
Potassium Ions
3 Substances found at higher concentrations INTRACELLULARLY
Sodium
Calcium
Chlorine
3 Substances found at higher concentrations EXTRACELLULARLY
Diffusion
Osmosis
Mediated Transport
Vesicular Transport
4 Methods ions and molecules use to cross the plasma membrane
Diffusion
The tendency for ions and molecules to move from an area of higher concentration to an area of lower concentration in a solution
Solution
Any mixture of liquids, gases, or solids in which substances are uniformly distributed with no clear boundaries between the substances
Solute
In a solution, it is the substance that is dissolved
Solvent
In a solution, it is the substances that is doing the dissolving
Concentration Gradient
The concentration difference between two points divided by the distance between the two points
Down (or with)
Molecules are said to move this way with their concentration gradient
Equilibrium
Diffusion stops when molecules are uniformly distributed throughout a solution. This means that the solution has achieved what?
Rate of Diffusion
As the concentration gradient increases, so does this
Osmosis
The movement of water across a selectively permeable membrane
Aquaporin(s)
Another name for water channels
Water Channel(s)
In some cells, rapid movement of water occurs through these
Osmotic Pressure
The force required to prevent the movement of water across a selectively permeable membrane
Hydrostatic Pressure
Pressure exerted by a volume of fluid against a wall, membrane, or some other structure that encloses the fluid
Isosmotic
Solutions having the same concentration of solute particles and the same osmotic pressure
Hyperosmotic
A solution having a greater concentration of solute particles and osmotic pressure than another solution
Hyposmotic
A solution having a lower concentration of solute particles and osmotic pressure than another solution
Hypotonic
When comparing two solutions, the solution with the lesser concentration of solutes and higher concentration of water

Cell will SWELL in this solution
Hypertonic
When comparing two solutions, the solution with the greater concentration of solutes and lower concentration of water

Cell will SHRINK in this solution
Lysis
Process in which a cell ruptures
Isotonic
When comparing two solutions, the solutions have the same concentration of solutes and the same concentration of water

Cell will REMAIN UNCHANGED in this solution
Mediated Transport
The process by which transport proteins assist in the movement of ions and molecules across the plasma membrane
Specificity
This means that each transport protein moves only particular ions or molecules, but not others

Example: Transport protein moves glucose, but not amino acids
Competition
This occurs when similar molecules or ions can be moved by a transport protein. The ion or molecule in the greater concentration, or for which the transport protein is MORE specific would be moved first
Saturation
The rate of movement across the membrane is limited by the number of available transport proteins

Once the concentration of the substance is increased so that all transport proteins are in use, the rate of movement remains constant, even if the concentration continues to increase

This means that the cell has reached this level
Channel Protein(s)
These proteins form membrane channels
Ion Channel(s)
Membrane channels that transport ions
Carrier Protein(s)
Membrane proteins that move ions or molecules from one side of the plasma membrane to the other

They have specific binding sites

They change shape to move bound ions or molecules, then resume their original shape
Transporter(s)
Another name for carrier proteins
Uniport
Movement of ONE specific ion or molecule across the membrane
Symport
Movement of TWO or MORE different ions or molecules, in the SAME direction, across the plasma membrane
Antiport
Movement of TWO or MORE different ions or molecules, in DIFFERENT directions, across the plasma membrane
Facilitated Diffusion
When carrier proteins combine with substances and move them across the plasma membrane

No ATP is used
ATP-Powered Pump(s)
Transport proteins that use energy derived from the breakdown of ATP to move specific ions or molecules from one side of the plasma membrane to the other
ATP
Adenosine Triphosphate
Active Transport
The movement of ions or molecules by an ATP-powered pump
ADP
ATP breaks down to this substance
Sodium-Potassium Pump(s)
Pump that moves Na out of a cell and K into a cell

Requires ATP
Secondary Active Transport
The concentration gradient established by active transport can provide enough energy to move a second substance by this method
Vesicular Transport
The movement of materials by vesicles into, out of, or within cells
Endocytosis
Vesicular transport INTO a cell
Exocytosis
Vesicular transport OUT of a cell
Phagocytosis
"Cell-eating"

The elimination of harmful substances by macrophages
Pinocytosis
"Cell-drinking"

The uptake of small droplets of extracellular fluid by the formation of small endocytic vesicles
Receptor-Mediated Endocytosis
When a specific molecule binds to its specific receptor

BOTH the molecule and receptor are transported into the cell by this process
Hypercholesterolemia
Common genetic disorder

Reduction or absence of LDL receptors on cell surfaces resulting in inadequate uptake of cholesterol

Excess cholesterol accumulates in blood vessels, resulting in heart attack or stroke
DNA
Deoxyribonucleic Acid

Mostly found within the nucleus (small amounts can also be found in the mitochondria)
Chromosome(s)
Threadlike structure within the nucleus containing the genetic information that is passed from one generation of cells to the next
Histone(s)
Protein molecule around which DNA is tightly coiled in chromatin
Chromatin(s)
Long strands of DNA found in the cell nucleus; condense to form chromosomes
Chromatid(s)
Each chromosome consists of two of these
Centromere(s)
Area where the chromatids of a chromosome are attached
Kinetochore(s)
A structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle
RNA
Ribonucleic Acid
Nucleoli
1 to 4 per nucleus

Rounded, dense, well-defined nuclear bodies with no surrounding membrane
Cisternae
Interior spaces of sacs and tubules in the Endoplasmic Reticulum
Cristae
Inner membrane (folded) of the Mitochondria
Matrix
The space between the cristae of the Mitochondria
Spindle Fiber(s)
Microtubules that extend out in all directions fro the centrosome
Nucleotide(s)
DNA and RNA are made of these
Double-Stranded
DNA is this shape (resembles ladder)
Single-Stranded
RNA is this shape
Gene
All the "triplets" necessary to make a functional RNA molecule or protein
Messenger RNA
mRNA
Ribosomal RNA
rRNA
Transfer RNA
tRNA
mRNA
Copy of DNA sequence used to make proteins by means of translation
tRNA
Carries amino acids to the ribosomes to make proteins by means of translation
Transcription
The process whereby the DNA sequence in a gene is copied into mRNA
RNA Polymerase
Enzyme used to make mRNA
Posttranscriptional Processing
Process that modifies mRNA before it leaves the nucleus in the form of mRNA

Removes introns

Splices exons together
Exon(s)
Sequence of nucleotides on a gene that gets transcribed and translated
Intron(s)
Sequence of DNA that is not involved in coding for a protein
Alternative Splicing
Process combining exons into mRNA

Allows single gene to produce more than one specific protein
Genetic Code
Total information contained in mRNA
Codon(s)
Set of 3-nucleotide sequence found in mRNA
Start Codon
Specific codon that codes for the beginning of a protein

Signals the beginning of translation

AUG - Methionine
Stop Codon(s)
Specific codon that codes for the end of a protein

Signals the end of translation

UAA, UGA, or UAG
Translation
The synthesis of proteins in response to the codons of mRNA
Anticodon(s)
Set of 3-nucleotide sequence found in tRNA

Complementary to mRNA
Polyribosome
Cluster of ribosomes attached to the mRNA
Posttranslational Processing
Process where modifications are made to proteins after they are produced
Ribosome(s)
Consist of rRNA and proteins

Align the codons of mRNA and the anticodons of tRNA
Proprotein(s)
Longer proteins

Before extra pieces of the molecule are cleaved off
Cell Division
The formation of 2 daughter cells from a single parent cell
Gamete(s)
Sex cells
Egg Cell(s)
Female gamete
Sperm Cell(s)
Male gamete
Diploid Number
The normal number of chromosomes in a somatic cell is called its?
Haploid Number
The normal number of chromosomes in a gamete is called its?
Somatic Cell(s)
All cells of the body except sex cells are called these
46
Number of diploid chromosomes in a human
23
Number of haploid chromosomes in a human
XX (Chromosomes)
Female sex chromosomes
XY (Chromosomes)
Male sex chromosomes
Meiosis
Cell division that produces reproductive cells in sexually reproducing organisms
Mitosis
Cell division in which the nucleus divides into nuclei containing the same number of chromosomes
Interphase
The period between cell divisions
Prophase
Metaphase
Anaphase
Telophase
4 Phases of Mitosis
Prophase
1st phase of mitosis (longest phase)

Chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus
Metaphase
2nd phase of mitosis

Chromosomes line up across the center of the cell
Anaphase
3rd phase of mitosis

Chromosomes move toward opposite ends of the nuclear spindle
Telophase
4th phase of mitosis

Nuclear membrane forms around each set of new chromosomes
Cytokinesis
Division of the cytoplasm during cell division
Cleavage Furrow
The first sign of cytokinesis
Differentiation
Process by which cells develop specialized structures and functions