Chapt 4 Flashcards
1
Q
There is a relationship between the size and _________ of a cell and it’s _____________
A
Shape; function
2
Q
What is the plasma membrane of a cell & its function
A
Cell membrane that forms a barrier separating the internal cal fluid & external fluid environment
3
Q
What is a nucleus & its function
A
Largest organelle enclosed in a nuclear envelope. Contains DNA, nucleoplasm (fluid), & nucleolus
4
Q
What is cytoplasm & its function
A
Cellular contents located between the membrane & nucleus, includes cytosol, organelles, & inclusions
5
Q
What is cytosol
A
Intracellular fluid
6
Q
What are organelles & what are the two types
A
Little organs that have a unique function & shape
- membrane bound: enclosed by a membrane
- non-membrane bound: not enclosed by a membrane
7
Q
What are inclusions in the cell
A
Aggregates of molecules (melanin & nutrients)
8
Q
What are the general cell functions
A
- Maintain integrity & shape of cell
- obtain nutrients & form chemical building blocks
- dispose of wastes
9
Q
What are phospholipids in the cell
A
Lipids of the plasma membrane
10
Q
What is the phospholipid bilayer
A
Framework of the cell’s plasma membrane
11
Q
What role does cholesterol play in the cell
A
Strengthens the membrane & stabilizes the membrane
12
Q
What are glycolipids & where are they located in the cell
A
Lipids attached to carbs; located on the outer surface
13
Q
What is glycocalyx
A
Formed by the glycolipid & glycoprotein; each person has their own pattern except identical twins
14
Q
What are the functions of the plasma membrane
A
Physical barrier, selective permeability (regulates entry & exiting of ions, nutrients, & waste), electrochemical gradients/establishes & maintains an electrical charge difference between the ICF & ECF, & communication (contains receptors that recognize & respond to a molecular signal)
15
Q
What are the types of membrane proteins
A
- Integral proteins
- peripheral proteins
- transport proteins
- cell surface receptors
- identity markers
- enzymes
- anchoring sites
- cell adhesion proteins
16
Q
What are integral proteins
A
Embedded within & extend across the plasma membrane
17
Q
Glycoproteins are what type of protein & what do they consist of
A
Integral protein; proteins w/ carbs
18
Q
What are peripheral proteins
A
Not embedded within but are attached loosely to the external or internal surfaces of the membrane
19
Q
What are transport proteins & what are the types
A
Regulate the movement of substances across the membrane; channels, carriers, pumps, symporters, & antiporters
20
Q
What are cell surface receptors
A
Bind molecules called ligands
21
Q
What are ligands & what membrane protein binds them
A
Molecules that bind to macromolecules; cell surface receptors
22
Q
What are identity markers
A
Communicate to other cells that they belong to the body
23
Q
What are enzymes as a membrane protein
A
Attached to either the internal or external surface; catalyzes reactions
24
Q
What are anchoring sites
A
Secure the cytoskeleton to the plasma membrane
25
What are cell adhesion proteins
Regulate cell-to-cell attachments
26
What is membrane transport within The cell & its types (just name)
Process that describes the entry or elimination of substances across the plasma membrane
Passive & active process
27
What is the passive process in membrane transport
Does not require cellular energy but moves a substances kinetic energy to move it down its concentration gradient
28
What is the active processes of membrane transport
Requires cellular energy because moves a substance up its concentration gradients
29
What are examples of passive membrane transport
Diffusion and osmosis
30
What are conditions that affect the rate of a substances diffusion
1.) the steepness of a concentrationgradient (difference in the concentration of a substance between 2 areas); steeper the gradient, the faster diffusion
2.) temp: the higher the temp, the higher the kinetic energy of a substance, the greater the rate of diffusion
31
What is diffusion & what type of membrane transport is it
net movement of a substance from high to low concentration, continues until substances reach equilibrium (molecules equally distributed), passive
32
What are the types of cellular diffusion
Simple, facilitated, channel-mediated, carrier mediated
33
What is simple diffusion
Solutes that are small & nonpolar & move down their concentration gradient; no transport protein is required & can cross the plasma membrane on its own
34
What is facilitated diffusion
Solutes that are small but charged & polar & cannot pass through the hydrophobic region of the membrane; require assistance to be transported in & out of the cell
35
What is channel-mediated diffusion
Movement of small ions across the plasma membrane thru water-filled protein channels
36
What are the 2 types of channels in a channel-mediated diffusion
Leak channel: specific to one ion & is continuously open
Gated channel: usually closed but opens in response to a stimulus (chemicals, light, voltage) & then stays open for a few seconds before reclosing
37
What is carrier-mediated diffusion
Movement of small polar molecules (sugars or amino acids) by a carrier protein
38
What is a carrier protein & A uniporter
- Transports substances (like glucose) after binding to it; then changes shape before the substances are moved to the other side
- a carrier protein that transports only one substance
39
What is osmosis
Passive movement of water thru the plasma membrane due to the different concentrations of water on either side of the membrane
40
What are aquaporins & where are they located
Integral protein water channels
41
What is a permeable solute & some examples
Pass thru bilayer ( O2, CO2, and Urea)
42
What ave non-permeable solutes & examples
Prevented from crossing the bilayer (charged, polar, or large solutes like ions, glucose, & proteins)
43
What is concentration gradient across the plasma membrane
Differences in solute concentration exist been ICF & ECF because of the regulated transport of solutes
44
Water moves ___________ its concentration gradient until it reaches ____________________
Down; equilibrium
45
Water moves in the direction of _____________ solute concentration
Higher (or less water concentration)
46
What is osmotic pressure
Pressure exerted by the movement of water across a semipermeable membrane due to the difference in solute concentration
47
What is hydrostatic pressure
Pressure exerted in a fluid on the inside wall of its container
48
Water movement across the cell can affect the cells ___________
Shape
49
What is tonicity
The change in shape thru volume & pressure changes by the movement of water
50
What is isotonic
Equal solute concentration between the ICF and ECF, & therefore the movement of water into & out of cell is constant; no change in cell shape
51
What is hypotonic
Lower concentration of solutes in the ECF than in ICF, so water
Enters the cell & exits ECF; cells volume increases & cell swells
52
What is lysis & what tonicity can it happen with
Cell rupture; hypotonic
53
What is hemolysis & what tonicity can it happen
Rupture of erythrocytes (RBC’s) & hypotonic
54
What is a hypertonic solution
Higher concentration of solutes in the ECF than ICF, so water exits the cell & enters the ECF; cells volume decreases & cell shrinks
55
What is crenation & what tonicity relates
Cell shrinking; hypertonic
56
What is active transport & its types
Movement of a solute against its concentration gradient (low to high concentration); primary active transport & ion pumps
57
What is primary active transport
Energy is captured from the breakdown of ATP to more substances across the membrane (usually called pumps)
58
What are ion pumps
They pump ions across the membrane up their gradient
59
What are sodium potassium pumps
An exchange enzyme pump that hydrolyzes ATP
60
What is the process of a sodium potassium pump
1.) 3 sodium ions & ATP bind sites on the pump in the ICF
2.) ATP is split into ADP & Pi, the pump changes shape & release Na+ into the ECF, while the free Pi remains attached
3.) 2 potassium ions from the ECF bind to the pump, the Pi is released
4.) the pump undergoes another shape change, releasing K+ into the ICF
61
What is secondary active transport
Moves substances up its concentration gradient by using energy provided by another substance being transported via kinetic energy
62
What is symport
Movement of the 2 substances in the same direction (ex. Glucose/Na+ symporter)
63
What is an antiport
Movement of the 2 substances opposite directions (ex.Na+/H+ antiporter)
64
What is vesicular transport (aka bulk transport) & what are the types
Requires energy to move large material via vesicular transport; exocytosis, endocytosis, phagocytosis, pinocytosis
65
What is a vesicle
Membrane bound sac filled with materials
66
What is exocytosis
Secretion of large substances or large amounts from the ICF to ECF
67
What are the steps of exocytosis
1.) a vesicle within the ICF nears the plasma membrane
2.) the vesicle fuses with the plasma membrane
3.) the plasma membrane opens toward the ECF
4.) release of substances in the vesicle occurs & the vesicle membrane integrates into the plasma membrane
68
What is endocytosis
Uptake of large substances or large amounts of substance from the extracellular fluid into the intracellular fluid
69
What is invagination
Small area of plasma membrane folds inward into the cytosol
70
What is phagocytosis
Cellular eating
71
What are the steps of phagocytosis
1.) cell forms extensions called pseudopodia to surround the particle
2.) once surrounded it gets enclosed within a membrane sac called a vesicle
3.) vesicle is moved into the ICF where it fuses with a lysosome so that the material can be degraded
72
What is pinocytosis
Cellular drinking; occurs when cells internalize droplets of ECF
73
What is receptor-mediated endocytosis & what does it allow the cell to do
Uses receptors on the membrane to bind molecules within the ECF & bring them into the cell; allows the cell to obtain bulk quantities of certain substances
74
What are examples of receptor - mediated endocytosis
- Transport of cholesterol from blood to cell
- cholesterol is bound to a lipid transporter called low-density lipoprotein (LDL)
- LDL's move can be moved into the cell via receptor-mediated endocytosis when they bind to the cell's LDL receptor
75
What is membrane potential
The form of potential energy stored in the electrical charge difference between the ECF & ICF
76
What is resting membrane potential (RMP)
Membrane potential of a cell at rest
77
What are the requirements of establishing & maintaining RMP
- Must be an unequal distribution of ions & molecules across the cell's membrane
- the amount of positive & negative charges are not equally distributed at the membrane
78
What does the nucleus do & produce
Houses DNA molecules that serve as the genetic instructions for the synthesis of proteins; produces ribosomal subunits in the nucleolus, which are exported into the cytoplasm for assembly into ribosomes
79
What is the nuclear envelope
Double membrane that encloses the nucleus
80
What is the nucleoplasm
Fluid located within the nucleus
81
What are nuclear pores
Open passageways formed by proteins that extend thru the nuclear envelope
82
What is the nucleolus
Produces the large & small ribosome subunits
83
What are the 4 deoxyribonucleotides
A-adenine
G-guanine
C-cytosine
T-thymine
84
What are histones
Nuclear proteins that wind DNA
85
What is a nucleosome
Complex created by histones
86
What is chromatin
Mass of DNA found in non-dividing cells
87
What is a chromosome
Tightly coiled masses of chromatin in dividing cells
88
What are genes
Segments of nucleotides within DNA that provide instructions for protein synthesis
89
What is transcription & where does it occur
Formation of an RNA copy from a DNA gene; nucleus
90
What is translation & where does it occur
Synthesis of proteins by ribosomes from the RNA copy; cytosol
91
What are the ribonucleotides
A-adenine
G-guanine
C-cytosine
U-uracil
92
What does RNA polymerase do in the process of transcription
Assembles the ribonucleotides by complementary base pairing RNA nucleotides with DNA
93
How are the nucleotides between DNA & RNA held together
Hydrogen bonds
94
What is the first major event in transcription & what happens
Initiation; DNA double helix is unwound by DNA Helicase
RNA polymerase synthesizes RNA by binding to the promoter sequence (start point) of the gene
* RNA polymerase reads only 1 strand of DNA double helix
95
What is messenger RNA (mRNA)
Copy of DNA that exits the nucleus
96
What is a template strand
Strand of DNA that is copied into RNA (mRNA)
97
What is the coding strand
Uncopied version of DNA
98
What is the 2nd major event of transcription & what happens
Elongation; as RNA polymerase moves down DNA template strand, free ribonucleotides of RNA (A, U, G, C) are base-paired with the deoxyribonucleotides of the template strand
* mRNA is lengthened in the process
99
What is the 3rd major event in transcription & what happens
Termination; when RNA polymerase reaches the terminal region of the gene, it releases the DNA & mRNA
* DNA rewinds into double helix and the mRNA is a copy of the gene that will be used to translate protein
100
What is translation & where does it occur
Synthesis of a new protein that takes place at the ribosomes
101
What is a required structure for translation
Ribosomal RNA (rRNA): two subunit organelle
102
What 3 spaces does alarge subunit consist of & what occurs at each one
A - aminoacyl site: where new amino acids are added
P-peptidyl site: where the newly forming polypeptide is held
E-exit site: where the empty tRNA is held
103
What happens in the initial stage oftranslation
- The small ribosomal subunit, the mRNA strand, & the charged tRNA come together first at the start codon
- the large ribosomal subunit binds to the small subunit positioning the tRNA in the P site
104
What is a codon
Each 3 base unit of ribonucleotides
105
What is a start codon
Signal for the beginning of translation (AUG)
106
What is a stop codon
The point where mRNA translation ends
107
mRNA is what is transcribed from DNA & read (translated) into protein. mRNA is read ______ bases at time
3
108
What happens in the elongation part of translation
- A charged tRNA with a complimentary anticodon base pairs with the codon of the mRNA in the A site
- a peptide bond forms between amino acids, releasing the "Met" from its tRNA
- the ribosome more 3 nucleotides (1 codon) down the mRNA strand
- the uncharged tRNA is released & process repeats
109
What occurs in the termination step of translation
- Occurs when a stop codon is reached
- the ribosomes disassemble, & the newly synthesized protein & mRNA are released,
110
What is a polyribosome
An mRNA with many ribosomes along its length
111
What are the functions of the rough ER & what type of organelle
Synthesis: synthesizes proteins for secretion, incorporation into plasma membrane, & as enzymes within lysosomes
Processing molecules: modify & store proteins
Organelle formation: helps for peroxisomes
Vesicle formation: forms transport vesicles for shipping of proteins to Golgi apparatus
* membrane-bound organelle
112
What are the functions of smooth ER & what type of organelle is it
Synthesis: site of lipid synthesis
Processing molecules: carbohydrate metabolism
Organelle formation: detoxifies drugs & poisons
Vesicle formation: forms transport vesicles for shipping to Golgi apparatus
* membrane bound
113
What are the functions of the Golgi apparatus
Synthesis: forms proteoglycans
Processing molecules: modify & store protein
Organelle formation: synthesizes digestive enzymes for lysosomes
Vesicle formation: forms secretary vesicles for delivering components of the plasma membrane & releasing contents from the cell by exocytosis
114
What is the process of proteins from ribosomes in the RER
- Ribosomes in RER synthesize protein & package it into transport vesicle
- vesicle leaves RER & fuses with Golgi apparatus
- proteins are modified as they move thru the Golgi apparatus
- modified proteins are packaged into secretory vesicles & released from the Golgi
- secretary vesicles either
- merge w/ plasma membrane & insert contents into the membrane or release proteins via exocytosis
- merge with lysosomes
115
What do lysosomes do
Digestion: break down molecules by fusing with resides, remove damaged organelles & cellular components, & break down cellular components(autolysis)
116
What do peroxisomes do
Digestion: break down fatty acids, amino acids, & urea w/ hydrogen peroxide
Synthesis: helps form certain lipids (ex. Bile salts)
117
What is included in the endomembrane system
Plasma membrane, nuclear envelope, & various membrane- bound structures that include the ER - Golgi apparatus, lysosomes & peroxisomes
118
What is the function of mitochondria
Energy harvesting: digest organic molecules to produce ATP by aerobic cellular respiration (aka powerhouse)
119
What do ribosomes consist of & the 2 types
Consist of a large & small subunit
- bound ribosomes: attached to external surface of RER membrane
- free ribosomes: suspended within the cell
120
What do bound ribosomes synthesize
Proteins destined to be fused with the plasma membrane, exocytosis from the cell, housed within lysosomes
121
What do free ribosomes synthesize
Proteins for use within the cell
122
What forms the cytoskeleton & what are its functions
3 different proteins (microfilaments, intermediate filaments,microtabules)
- Structural support: maintains cell shape, protein support of microvilli, cilia, & flagella; stabilizes cell junctions; organizes organelles
- cell division: separates chromosomes during cell division & splits cells into 2 daughter cells
- movement: facilitates cytoplasmic streaming; involved in the movement of vesicles within a cell; participates in muscle contraction
123
What are The functions of the centrosome
Synthesis: organizes microtubules & supports their growth in non-dividing cells
Cell division: directs the formation of the mitotic spindle in dividing cells
124
What are the functions of proteasomes
Protein digestion: degrades proteins that are damaged, incorrectly folded, or are no longer needed
Quality assurance: controls the quality of exported cell proteins
125
What is cilia
Hair-like projections that move mucus toward the throat so it can be expelled from the respiratory tract
126
What is flagella
Whip-like structure that helps propel sperm
127
What is microvilli
Thin microscopic extensions that increase the plasma membranes surface area to increase membrane support
128
What are membrane junctions
Connect & support cells
129
Where is a tight junction located & what is it
Located at apical surfaces of adjacent cells & function to seal off the intracellular space & prevent substances from passing between cells
130
What are desmosomes, where are they located, & what do they do
Consist of protein plaques & filaments, located on the internal surface of the plasma membrane of adjoining cells, provide structural integrity to the cells exposed to stress
131
What are gap junctions & connexons
Provides a direct passageway for substances to travel between neighboring cells
- transmembrane protein
132
What is mitosis
Somatic cell division of nucleus
133
What is meiosis
Sex cell division of the nucleus
134
What is a somatic cell
All cells but sex cells
135
What are daughter cells
2 identical cells that arise after a cell undergoes cell division
136
What is the broad definition of interphase
Cellular preparation for division (3 steps)
137
What happens in the G1 stage of interphase
Cells grow and produce double their organelles
138
What happens in the S phase of interphase & what are the required materials
DNA strands are duplicated; DNA polymerase & a large # of deoxyribonucleotides
139
What happens in the G2 phase of interphase
Centrioles are completely replicated, & enzymes needed for cell division are created
140
What are sister chromosomes
Replicated DNA strands
141
What is a centomere
A region that keeps the sister chromatids joined together
142
When do chromosomes form in the major phase
At the separation of sister chromatids
143
What happens in the prophase stage
Chromosomes appear as chromatin coil
Nucleolus & nuclear envelope disappear
Spindle fibers from centrioles form ascentrioles move to opposite ends of the cell
144
What happens during metaphase stage
Centromeres on chromosomes attach to spindle fibers(centriole) & they align along the equatorial plate
145
What is the anaphase stage
Sister chromatids move toward opposite ends of the cell (sister chromatids are now called chromosomes), & cytokinesis begins creating a cleavage furrow (pinching in the cell)
146
What happens in telophase stage
Chromosomes uncoil to form chromatin
A nucleolus re-forms within each nucleus
Spindle fibers break up & disappear
Nuclear envelope forms around each set of chromosomes
Cytokinesis continues as cleavage furrow deepens
147
What is cytokinesis
Division of cytoplasm between two newly formed cells
148
What is a cleavage furrow
Intention created by the contraction of microfilament proteins( located in the plasma membrane) at the cells equator
