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Semester 2 > Cell physiology > Flashcards

Cell physiology Flashcards

1
Q

Animal cells – 3 compartments

A

1) cell membrane

2) cytoplasm

3) nucleus

protoplasm = cytoplasm + nucleus

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2
Q

functions of plasma membrane

A

1) barrier b/w cell & environment
(cells, ISF/plasma)

2) SELECTIVELY PERMEABLE MEMBRANE

3) I.e. UNIQUE internal cell environment

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3
Q

cell membrane structure

A

75% phospholipids

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4
Q

phospholipids are…

A

amphipathic

both polar and non-polar components

nonpolar fatty acid tails
polar phosphate head

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5
Q

cell membrane structure (bilayer)

A

high amounts of phospholipids in aqueous solution

= phospholipid bilayer

= phosphate heads towards water, FA tails away from water (towards each other)

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6
Q

majority of phospholipid bilayer is (hydrophilic? hydrophobic?)

A

hydrophobic (tails)

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7
Q

consequence of majority hydrophobic bilayer

A

only hydrophobic (non-polar) molecules can pass through

hydrophilic (polar) molecules need carrier/channel mediation

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8
Q

exception to what can/can’t typically pass through lipid bilayer

A

Size is important variable

some small polar molecules can pass through – even though polar

some large nonpolar molecules may need transport (?) – even though nonpolar

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9
Q

permeable to…

A

Non-polar, hydrophobic, uncharged, (small?) – E.G. STEROIDS, O2, CO2

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10
Q

impermeable to…

A

polar, hydrophilic, charged – E.G. IONS, LARGE PROTEINS

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11
Q

example of exception

A

H2O – permeable to some degree – even though POLAR, HYDROPHILIC

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12
Q

what happens if lose selective permeability?

A

cell would no longer be able to maintain homeostasis – would be destroyed

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13
Q

lipid bilayer is composed of which lipids?

A

75% phospholipids

20% cholesterol

5% glycolipids

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14
Q

cholesterol in the lipid bilayer

A

carries a (polar) OH group (HYDROXIL GROUP)

attaches to phosphate group (polar head)

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15
Q

function of cholesterol in lipid bilayer

A

structure @ high temp
fluidity @ low temp

1) maintains structure @ high temperatures

(by keeping phospholipids locked together)

2) maintains fluidity of membrane @ low temperatures

(Non-polar portion prevents phospholipids (tails?) interacting)

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16
Q

GLYCOLIPIDS in the lipid bilayer

A

sugar attached to lipid

FOUND ON EXTRACELLULAR SIDE

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17
Q

which side are glycolipids?

A

extracellular side

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18
Q

function of GLYCOLIPIDS in cell membrane

A

SIGNAL TRANSDUCTION (convert signal type)

CELL TO CELL ADHESION

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19
Q

what is GLYCOCALYX composed of?

A

“sugary coat”

composed of carbohydrate portion of glycolipids (& glycoproteins)

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20
Q

function of GLYCOCALYX

A

1) cell recognition/signalling

2) protection

3) regulates cell behaviour

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21
Q

Cell membrane PROTEIN categories

A

1) Integral proteins

2) Peripheral proteins

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22
Q

integral proteins

A

crosses bilayer (“embedded”)

contains both polar/nonpolar parts (AMPHIPATHIC?)

complex/large

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23
Q

peripheral proteins

A

on surface of membrane (external or internal side)

attach to polar head of phospholipid

or attach to integral proteins

less complex/large

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24
Q

membrane proteins functional types

A

1) Transporters

2) Ion Channels

3) Receptors

4) Enzymes

5) Linkers

6) Markers

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25
Q

1) Transporters

A

INTEGRAL

transports POLAR molecules

E.g.
GLUCOSE transporter
AMINO ACID transporter

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26
Q

2) Ion Channels

A

INTEGRAL

transports IONS

can be…
ONE WAY
TWO WAY
SINGLE ION
MULTI ION

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27
Q

3) Receptors

A

INTEGRAL

“lock & key”

Takes specific LIGAND

E.G
INSULIN & IT’S RECEPTOR

“ligare” – to bind

HORMONE IS LIGAND, BUT LIGAND NOT ALWAYS HORMONE

Hormone = type of ligand

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28
Q

4) Enzymes

A

INTEGRAL OR PERIPHERAL
Active side faces inside or outside cell

Acts on SUBSTRATE

1) Breaks down SUBSTRATE –> products

2) CATALYZES REACTIONS (accelerate/cause)

E.G.
LACTASE protruding from EPITHELIAL cells of small intestine
–> breaks down lactose

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29
Q

5) Linker

A

Integral or peripheral

attach/link other proteins
attach/link other cells

STRUCTURAL STABILITY of membrane

E.G.
Blood clots via fibrinogen and platelets

holds filaments inside/outside membrane

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30
Q

6) Markers

A

cell identity

MAJOR HISTOCOMPATIBILITY PROTEINS

MHC proteins
–> ON OUTSIDE OF IMMUNE CELLS (e.g. macrophage)

Display peptide fragment from PATHOGENS to T-cells for recognition

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31
Q

miscellaneous fact about drugs and membrane proteins

A

membrane proteins are target of over 60% of all drugs

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32
Q

Fluid mosaic model

A

fluid movement of phospholipids

= membrane fluidity

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33
Q

cell types examples

A

nerve cell

sperm cell

egg cell

skin

muscle

bone

immune

fat

epithelial

etc.

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34
Q

two types of transport

A

1) Passive transport
2) Active transport

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35
Q

passive transport does not require

A

energy, ATP

uses potential energy

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36
Q

passive transport, where does energy come from?

A

electric gradient
concentration gradient

solutes move down gradient

potential energy (gradient) becomes kinetic

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37
Q

how is membrane gradient created

A

selective permeability

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38
Q

resting membrane potential

A

neurons and muscle fibres

facilitates Action Potentials (nerve impulse)

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39
Q

2 Types of Passive transport

A

1) Diffusion (solutes)

2) Osmosis (water)

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40
Q

Variables affecting Rate of Diffusion

A

1) Temperature

2) Surface area

3) Ratio of gradient

4) Size of particles

5) Thickness of membrane
(distance)

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41
Q

2 types of Diffusion

A

1) Simple Diffusion
(directly through membrane)

2) Facilitated Diffusion
(transmembrane (integral) protein)

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42
Q

why facilitate diffusion?

A

larger, polar, hydrophilic/charged molecules

e.g.
Ions
hormones
drugs

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43
Q

Facilitated diffusion via..

A) (Ion) Channel protein or
B) Carrier (transporter) protein

A

(ion) channel…
DOES NOT CHANGE SHAPE
OPENS OR CLOSES
E.g.
Calcium ion
Potassium ion

carrier (tranporter)…
CHANGES SHAPE
E.g.
glucose
fructose
vitamins

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44
Q

gated channel protein

A

gate determines when ions can/can’t flow in

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45
Q

types of gated Channel proteins

(a type of facilitated diffusion, a type of passive transport)

A

LIGAND gate
(ligand, e.g. hormone)

VOLTAGE gate
(voltage change)

MECHANICAL gate
(pressure)

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46
Q

Leak channels (in contrast to gated channels)

A

leak channels always open

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47
Q

OSMOSIS (passive transport)

A

water from high concentration to low

When membrane impermeable to solutes

Via membrane directly
or
Via AQUAPORINS (channel proteins for water)
(“water pores”)

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48
Q

OSMOTIC PRESSURE

A

minimum pressure that needs to be applied to SOLVENT to prevent it from passing into a solution VIA OSMOSIS

measure of concentration of solution (?)
I.e. pressure is directly proportional to concentration of solute

Pressure is against SOLUTE-heavy (?) side

(Pressure required to return to starting conditions)

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49
Q

ONCOTIC pressure

A

colloid osmotic pressure

pressure in BLOOD PLASMA

via proteins (E.g. ALBUMIN)

ALBUMIN controls blood osmotic pressure
–> prevents fluid leaking out of Blood Vessels

PULL WATER BACK INTO VENOUS CIRCULATION

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50
Q

BCOP

A

Blood Colloid Osmotic Pressure

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51
Q

HYDROSTATIC PRESSURE

A

Pressure exerted by fluid on surroundings

EQUILIBRIUM–> HYDROSTATIC PRESSURE = OSMOTIC PRESSURE

in U-tube e.g. –> EQUILIBRIUM = UNEVEN WATER LEVELS

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52
Q

TONICITY & osmosis

A

CONCENTRATION of solutes in solution

measures ability to change volume by changing water content

HYPOTONIC solution
ISOTONIC solution
HYPERTONIC solution

“hypertonic” EXTERNAL solution relative to INTERNAL cell environment

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53
Q

hypertonic solution

A

= cell shrinks

“CRENATION”

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54
Q

hypotonic solution

A

= cell bulges (if beyond tolerated force, cell will rupture)

“LYSIS”

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55
Q

Active transport

A

Sodium Potassium Pump

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56
Q

Sodium Potassium Pump – which cell not found in

A

RBC

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57
Q

Sodium Potassium Pump – function

A

maintains resting membrane potential (RMP)

REMOVES 3 NA+ (ions)
BRINGS 2 K+ (ions)

Requires ATP

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58
Q

Sodium Potassium Pump establishes…

A

CONCENTRATION GRADIENT

ELECTRICAL GRADIENT
(i.e. RMP)

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59
Q

Concentration gradient via Na+K+ pump

A

more Na+ outside cell
more K+ inside cell

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60
Q

Electrical gradient via Na+K+ pump

A

more positive outside cell

more negative inside cell

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61
Q

RMP

A

every cell negative inside (negative RMP)

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62
Q

why negative RMP inside cell?

A

1) Na+K+ pump

2) more K+ (diffusion) channels (more permeable to K+ within cell

3) many negatively charged organic molecules inside cell (e.g. Proteins)

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63
Q

examples of RMP of various cells

A

neurons = -70mV
skeletal muscles = -90mV
smooth muscles = -60mV

photoreceptor cells = -40mV

RBC = -10mV

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64
Q

2 types of Active transport

A

Primary Active transport
(via ATP)

Secondary Active transport
(via kinetic energy released by concentration gradient (passive movement) of other solutes)

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65
Q

example of primary active transport

A

Na+K+ pump

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66
Q

2 types of Secondary Active transport

A

Symporters (move 2 substances in same direction)

Antiporters (2 substances in opposite direction)

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67
Q

Vesicular transport

A

Active (requires ATP)

1) ENDOCYTOSIS
2) EXOCYTOSIS

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68
Q

exocytosis

A

1) secretion of hormones
E.g.
insulin
oxytocin

2) excretion of wastes
E.g.
Urea (kidneys)

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69
Q

endocytosis

A

1) phagocytosis

2) pinocytosis

3) receptor-mediated endocytosis

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70
Q

1) phagocytosis

A

eat large particles

E.g.
cells, bacteria, virus

E.g.
WBC, PSEUDOPODS
monocyte
macrophage
neutrophil
dendritic cells
osteoclasts
eosinophil

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71
Q

2) pinocytosis

A

bulk-phase endocytosis

intake of fluid+solutes inside

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72
Q

function of pinocytosis

A

Controls cell volume

transports molecules

proves nutrients to cell via digestion of molecules (Via DIGESTIVE ENZYMES INSIDE VESICLE/lysosome)

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73
Q

receptor mediated endocytosis

A

selective endocytosis

targets specific LIGANDS (ions/molecules) –
Via receptor proteins?

receptor proteins recycled

goes to endosome

digested/destroyed in lysosome

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74
Q

TRANSCYTOSIS

A

combo of exocytosis and endocytosis

e.g.
antibodies cross placenta
(endocytosis to cell of placenta
exocytosis to other side toward fetus)

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75
Q

note terms:

A

phagosome
pinosome

lysosome
endosome

exosome

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76
Q

cytoplasm consists of

A

cytosol (fluid)

organelles

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77
Q

cytosol % of cell volume

A

55%

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78
Q

cytosol % that is water

A

70-90%

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79
Q

list of organelles

A

Cytoskeleton

Centrosome

Cilia & flagella

Ribosomes

Endoplasmic reticulum

Golgi complex

Vesicles

Mitochondria

Nucleus

Nucleolus

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80
Q

vacuole vs vesicle

A

Vacuoles are somewhat larger than vesicles, and the membrane of a vacuole does not fuse with the membranes of other cellular components

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81
Q

cytoskeleton 3 types

A

Microfilaments

Intermediate filaments

Microtubules

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82
Q

microfilament, intermediate filament, microtubule

orientation (?)

A

microfilaments close to membrane (?)

intermediate filaments in b/w (?)

microtubules closest to centre (?)

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83
Q

Microfilaments (protein?)

A

smallest of 3

ACTIN protein

usually near cell membrane

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84
Q

microfilaments functions

A

1) movement and support

2) Cytokinesis (cell division)

3) muscle contraction

4) connect cytoskeleton to integral proteins

5) form microvilli

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85
Q

intermediate filaments (protein?)

A

medium size

protein KERATIN

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86
Q

intermediate filaments function

A

1) internal stability

2) organelles in specific position

3) bind adjacent cells (cell junctions)

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87
Q

microtubules

A

largest

protein TUBULIN

long/hollow

made in CENTROSOME

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88
Q

microtubules functions

A

1) Cell’s shape

2) movement of organelles (e.g. vesicles)

3) movement of chromosomes during cell division

4) Cilia and the Flagellum
(9 + 2 arrangement of microtubules)

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89
Q

centriole vs centrosome

A

A centriole is a barrel-shaped organelle which lives normally within the centrosome.

Centrosomes are structures found inside of cells. They are made from two centrioles. Centrioles are microtubule rings. The main purpose of a centrosome is to organize microtubules and provide structure for the cell, as well as work to pull chromatids apart during cell division.

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90
Q

centrosome

A

Microtubule organize

mitosis & meiosis (cell division)

2 centrosomes in each cell

near the nucleus

91
Q

centrosome consists of

A

Centrioles
= a pair of cylindrical structures composed of 9 clusters of 3 microtubules

92
Q

pericentriolar material

A

Pericentriolar material

contains TUBULIN protein to help build microtubules

Surrounds the centrioles and forms the starting point for mitotic spindles during mitosis

93
Q

cilia

A

cilium singular

1) cell mobility (egg cells down the fallopian tubes)

2) sweep foreign particles along an epithelial lining (respiratory tract)

MADE OF MICROTUBULES

94
Q

flagella

A

flagellum singular

propels cell forward

only in sperm cells

95
Q

ribosomes made of

A

made of…
ribosomal proteins
rRNA

50% protein 50% rRNA in eukaryotes

96
Q

ribosome functions

A

protein synthesis (TRANSLATION)

free-floating vs attached to ROUGH ER

97
Q

free floating vs rough ER ribosomes function

A

floating =
produce proteins for use in cytosol

rough ER ribosomes =
proteins for…
A) organelles
B) cell membrane
C) exocytosis

98
Q

ribosome composition

A

2 subunits of rRNA
(Large unit and small unit)

made in nucleus
assembled in cytosol

tiny granules under a microscope

99
Q

ribosomes also found in…

A

mitochondria

for ENZYME synthesis
(one of SIX membrane protein types)

100
Q

Endoplasmic reticulum

A

network of flattened sacs

extend from nuclear membrane

smooth ER (no ribosomes)
rough ER

101
Q

smooth ER function

A

lipid production

phospholipids, cholesterol

102
Q

smooth ER in liver cells…

A

detoxify drugs

breaks down glycogen to glucose

103
Q

smooth ER in muscle cells…

A

called SARCOPLASMIC RETICULUM

stores/releases CA2+

104
Q

rough ER

A

protein synthesis

e.g.
integral membrane proteins

hormones

structural proteins

105
Q

rough ER continuous with…

A

nuclear membrane

106
Q

proteins of rough ER exported via

A

“secretory pathways”

107
Q

golgi complex

A

AKA
golgi apparatus
golgi body

Receive/modify/transport proteins from the rough ER

more complex/numerous Golgi body = larger secretory role.

108
Q

golgi complex sacs

A

has 3 small sacs (cisternae):

Entry/cis face
= CONVEX
= facing rough ER
= receives protein via transport vesicles

intermedias (medial) cisternae
= protein becomes glycoproteins or lipoproteins (via ENZYME)

Exit/trans face
= concave side
= releases product

109
Q

vesicles

A

formed by a lipid bilayer

separating contents from the cytoplasm or ECF

110
Q

vesicles examples

A

Lysosome

Peroxisome

Secretory Vesicles

111
Q

lysosome

A

digest substances (via enzymes)

Acidic pH for optimal enzyme function –> pH <7

A) Autophagy :
Removal of unnecessary or dysfunctional organelles

B) Autolysis:
self-digestion (destruction of entire cell)

112
Q

autophagy

A
113
Q

autolysis

A
114
Q

peroxisome

A

breakdown of some organic molecules (very long FAs)

Contains many digestive proteins

peroxisomes neutralize H2O2 (hydrogrenperoxide – byproduct of metabolism)

115
Q

Secretory vesicles

A

to the plasma membrane for exocytosis

e.g. proteins, hormones

116
Q

mitochondria

A

ATP via aerobic metabolism (requires O2)

via glucose, protein, lipids —> ATP

note gluconeogenesis

117
Q

mitochondria more numerous in…

A

muscle and nerve cells (active)

118
Q

mitochondria not present in…

A

RBC

119
Q

mitochondria structure

A

Structure:
outer and inner membrane

CRISTAE (folds) of inner membrane

between cristae is MATRIX
= most reactions take place
= Analogous with cytoplasm of the cell

Contain ribosomes
own set of DNA

ability to self-replicate proteins

120
Q

mitochondria DNA

A

DNA is different from the main set of chromosomes in the nucleus

Only one “mitochondrial chromosome”
many per mitochondria

Much small than DNA in nucleus (?)

Circular DNA (same as bacteria)

Maternal inheritance only

121
Q

mitochondria theory of origin

A

mitochondria are of bacterial origin

122
Q

nucleus

A

“Brain” of cell

responsible for…
genetics
protein synthesis

(analogous to the CPU of a computer)

The nucleus is where we find the DNA, our genetic material

123
Q

found in nucleus

A

the DNA, our genetic material

124
Q

how many nuclei?

A

Most cells have 1 nucleus (UNINUCLEATE)

some have more (i.e. muscle cells) = (MULTINUCLEATE)

some have NONE (i.e. mature red blood cells)

125
Q

nucleus structure

A

NUCLEAR ENVELOPE
= double membrane
= separates from cytoplasm
= like plasma membrane

NUCLEAR PORES
= substances in/out
= Proteins/hormones in
= RNA out

126
Q

Nucleolus

A

largest structure in the nucleus

spherical body

made of clusters of RNA & protein

Function is to make rRNA (ribosomes)

127
Q

DNA

A

double stranded helix

backbone of alternating pentose sugars and phosphate group

complementary nitrogenous base pairs form hydrogen bonds

128
Q

stretch out DNA in a cell

DNA in body

A

would be 6 feet long

would be 108 billion KM
(150,000 round trips to moon)

129
Q

genes

A

segments of DNA

encode for traits

codes for proteins that change structure/function/appearace

130
Q

how many genes in human genome

A

20,000 genes

less than 1/2 function is known

131
Q

genes examples

A

124 genes for hair colour
16 genes for eye colour
4 genes for freckles

132
Q

Allele

A

variation of DNA sequence at a GENOMIC location

E.g.
Allele for red hair
Allele for blonde hair
Allele for brown hair

133
Q

Genotype

A

sequence of base pairs in gene

“what genes say you should look like”

134
Q

Phenotype

A

observable traits form genotype

“what you look like”

135
Q

Histones

A

protein balls

DNA double helix coils around “

136
Q

Nucleosome

A

combination of histone and DNA double helix

137
Q

Linker DNA

A

section of DNA that links NUCLEOSOMES together

138
Q

Chromatin

A

DNA/RNA/proteins prior to cell division

scattered throughout nucleus before cell division

granular mass when cell not dividing

chromatin clusters –> forms chromosomes before cell division

139
Q

groups of NUCLEOSOMES = chromatin (???)

groups of CHROMATIN
=chromatin fibre (???)

A
140
Q

chromatin fibre

A

composed of chromatin

section of many NUCLEOSOMES & Linker DNA

141
Q

chromatin condensation

A

forms chromosome

142
Q

chromosomes

A

arrangement of chromatin fibres during cell division

143
Q

humans have…

A

46 chromosomes
23 from each parent

144
Q

pairs of chromosomes =

A

HOMOLOGOUS CHROMOSOMES

145
Q

AUTOSOMAL CHROMOSOMES

A

1-22

146
Q

chromosome 23

A

SEX CHROMOSOME

147
Q

SEX CHROMOSOME…

A

determines gender

female = xx
male = xy

148
Q

CHROMATIDS

A

1/2 of chromosome

1 pair chromatid = chromosome

149
Q

centromere

A

centre portion of chromosome

holds two CHROMATIDS together

(or 2 sister chromatids)

150
Q

TELOMERES

A

non-coding

terminal portion of chromosomes

protects end of chromosome

prevents genetic material loss when cell divides

become short eventually –> Cell can’t divide –> cell dies

151
Q

short telomere

A

increased disease/aging

152
Q

GENOME

A

total genetic info of organism

carried in nucleus of cells

153
Q

human genome project

A

2003
mapped out most of genome of human

20,000 genes

took 13 years

2022 –> genome almost entirely mapped

154
Q

number of genes correlation to intelligence

A

does NOT correlate with intelligence

155
Q

PROTEIN SYNTHESIS

A

new proteins from genome

ONLY IN CELLS W/ NUCLEUS

No nucleus = no DNA = no protein synthesis

E.g. RBC no nucleus

PROTEIN SYNTHESIS begins in NUCLEUS, end in CYTOPLASM

156
Q

protein synthesis 2 steps

A

1) Transcription
DNA –> mRNA

2) Translation
mRNA –> protein

157
Q

Transcription (Protein Synthesis)

A

transcribing DNA into RNA

all 3 types of RNA

occurs in NUCLEUS

158
Q

Transcription (RNA POLYMERASE)

A

RNA POLYMERASE
@ PROMOTER REGION

UNZIPS small section of DNA

(two strands separated)

159
Q

TEMPLATE STRAND

CODING STRAND

A

template strand is transcribed

coding strand is not

complementary nucleotide bases are matched

160
Q

on template strand, new nucleotides can only be added to which end?

A

3’ (3 prime) end

moves along strand in 3’ to 5’ (5 prime) direction

161
Q

complementary nucleotide bases (nitrogenous bases)

A

e.g.
A–> U (T replaced in RNA)
G–> C
T–> A
C–> G

162
Q

PROMOTER REGION
CODING SEQUENCE
TERMINATOR REGION

A

regions of gene

RNA polymerase starts at PROMOTER

ends at TERMINATOR region

RNA polymerase then detaches from DNA & pre-mRNA molecule

163
Q

SPLICING of pre-mRNA molecule (INTRONS and EXONS)

A

pre-mRNA molecule & snRNPs (Small Nuclear RiboNuclear Proteins)

snRNPs splice pre-mRNA
= moves non-coding segments (introns)
= splices coding segments (exons) together

164
Q

Alternative Splicing

A

same pre-mRNA molecule

different mRNA strands

different proteins

snRNPs will splice a pre-mRNA strand differently at different times to produce different mRNA strands which are then translated to different proteins (from the same pre-mRNA molecule)

165
Q

5’ (5 prime) cap

A

modified guanine nucleotide

1) “REGULATION of nuclear export”

2) structural stability

3) improve translation

166
Q

3’ (3 prime) poly-A tail

A

adenine nucleotides

1) REGULATION of nuclear export

2) structural stability of mRNA

3) facilitate translation

167
Q

where does mRNA go after?

A

after splicing & cap/tail –> pre-mRNA becomes mRNA –> EXITS NUCLEUS VIA NUCLEAR PORES

goes to cytoplasm

TRANSLATION OCCURS NEXT

168
Q

Codon

A

three nucleotide (nitrogenous) bases

each CODON in mRNA strand
= Codes for specific AMINO ACID

169
Q

start codon

vs

stop codon

A

start codon = translation initiates

stop codon = translation stops

170
Q

Translation

A

translating mRNA to polypeptide

NUCLEIC ACID –> AMINO ACID

performed by RIBOSOMES

in CYTOPLASM

171
Q

mRNA & Ribosome

A

mRNA attaches to SMALL ribosomal subunit (of 2)

ANTICODON of INITIATOR tRNA
binds to…
CODON of mRNA

(complementary bases)

172
Q

tRNA

A

takes appropriate AMINO ACID to POLYPEPTIDE

ANTICODON on tRNA binds to CODON of mRNA

anticodon determines AMINO ACID

173
Q

what happens after tRNA and mRNA connect?

A

LARGE RIBOSOMAL SUBUNIT attaches to SMALL SUBUNIT & mRNA

Creates functional ribosome

174
Q

functional ribosomes – 3 binding sites (for tRNA + AA)

A

A site
P site
E site

A site:
binds tRNA carrying next amino acid (“acceptor” site)

P site:
binds initiator tRNA
= tRNA carrying polypeptide chain

E site:
binds tRNA just before released from ribosome (“Exit” site)

175
Q

A site after P site

A

anticodon of another tRNA + AA pairs with mRNA Codon (in A site)

Peptide bond occurs between two AMINO ACIDS of two tRNAs

di-peptide attaches to tRNA on A-site

176
Q

shifting from A-site to P-site

A

Ribosome shifts both mRNA (and attached tRNAs) by ONE codon

A-site becomes open again

tRNA that enters E site EXITS

177
Q

when does translation end?

A

When Ribosome reaches STOP Codon on mRNA

protein detaches from final tRNA

ribosomal subunits separate

178
Q

which RNA types involved in TRANSLATION?

A

mRNA, tRNA

also rRNA because ribosomes made of rRNA

179
Q

what determines orders of AMINO ACIDS (& therefore structure of protein)

A

CODONS in mRNA (determined by DNA)

180
Q

free vs attached ribosomes

A

free produce proteins for cell

attached produce proteins for membrane, or exocytosis
(Enter ER & sent to Golgi body for processing before wrapped by VESICLE)

181
Q

POLYRIBOSOME (or POLYSOME)

A

multiple ribosomes TRANSLATING simultaneously

Why?
more proteins quicker
more efficient (less mRNA)

182
Q

2 types of cell division

A

1) MITOSIS
exact replica for growth/repair

2) MEIOSIS
creates gametes (sperm, ova)

183
Q

diploid vs haploid

A

2 sets of chromosomes = 46
= 2n or diploid
= n is number of distinct chromosomes

1 set of chromosomes = 23
= n or haploid

nearly all cells have 46 chromosomes
= 2 sets of 23
= one from each parent
= diploid

Gametes have 23
= sperm/ova
= haploid

184
Q

mitosis vs meiosis

A

mitosis:
= diploid SOMATIC cells replicate
= diploid becomes diploid

meiosis:
= diploid GERM cells replicate
= produce GAMETES
= diploid becomes haploid

185
Q

cell cycle

A

cycle for mitosis/meiosis to occur

186
Q

2 phases of cell cycle

A

1) INTERPHASE
2) MITOTIC PHASE (meiotic phase for meiosis)

(meiosis goes through cell cycle twice)

187
Q

mitosis

A

division of cell produces DAUGHTER CELLS

occurs in SOMATIC CELLS
occurs in GERM CELLS

diploid –> diploid

188
Q

mitosis and cell cycle

A

INTERPHASE
duplicate material

MITOSIS
divide contents

CYTOKINESIS
2 daughter cells separate

189
Q

1) INTERPHASE (mitosis)

A

1) increase cell size
2) duplicate organelles
3) duplicate DNA

190
Q

3 PHASES of INTERPHASE (mitosis)

A

G1 phase (growth 1)
S phase (Synthesis)
G2 phase

191
Q

G1 PHASE of interphase (mitosis)

A

cell grow
organelle duplicate

CENTROSOME duplication begins
(centrosome for division)

Note cell is metabolically active

192
Q

S PHASE of interphase (mitosis)

A

DNA duplicate (copy for each daughter cell)

1) DNA is unraveled via…
DNA HELICASE

2) complementary strands made via…
DNA POLYMERASE

3) = two identical copies of DNA

I.E.
92 CHROMOSOMES

193
Q

SISTER CHROMATIDS

A

I.E.
92 CHROMOSOMES(??? TYPO? SHOULD BE 92 CHROMATIDS INSTEAD?)

identical duplicate chromosomes

194
Q

G2 PHASE of interphase (mitosis)

A

growth

proteins/enzymes made

CENTROSOME duplication FINISHES

…

195
Q

MITOTIC PHASE of mitosis

A

PMAT (Mitosis) + Cytokinesis = MITOTIC PHASE

Prophase
Metaphase
Anaphase
Telophase

followed by CYTOKINESIS

196
Q

(early) PROPHASE (PMAT) phase of Mitotic phase (of Cell cycle)

A

early prophase:
CHROMATIN forms Chromosomes (via chromatin fibres)

Sister chromatids join to form X via Centromere

KINETOCHORE:
protein that stabilizes Centromere

REMINDER:
(histone –> nucleosome –> Linker DNA –> Chromatin –> Chromatin fibre –> Chromosome)

197
Q

(histone –> nucleosome –> Linker DNA –> Chromatin –> Chromatin fibre –> Chromosome)

A
198
Q

KINETOCHORE

A

KINETOCHORE:
protein that stabilizes Centromere

199
Q

(late) PROPHASE

A

nuclear envelope breaks

2 pairs of Centrosomes go to opposite ends

CENTRIOLES of centrosomes connect to CENTROMERES via…
MITOTIC SPINDLES

200
Q

MITOTIC SPINDLES

A

CENTRIOLES of centrosomes connect to CENTROMERES via…

201
Q

2) METAPHASE phase of Mitotic phase (cell cycle)

A

chromosomes aligned on METAPHASE PLATE (aka equatorial plate)

aligned in single line along middle of cell

202
Q

3) (early and late) ANAPHASE phase of mitotic phase (cell cycle)

A

early:
centromeres split apart via MITOTIC SPINDLES pull

towards Centrosomes

sister chromatids pulled apart

late anaphase:
plasma membrane begins to separate
= small CLEAVAGE FURROW

203
Q

4) TELOPHASE phase of mitotic phase (cell cycle)

A

Early telophase:
CLEAVAGE FURROW grows larger
–> chromatids at opposite ends (poles)

Late telophase:
separate NUCLEAR ENVELOPES form on each side

204
Q

Cytokinesis

A

plasma membrane forms separately around each DAUGHTER CELL

cells move apart

cell cycle / Mitosis complete

205
Q

Meiosis

A

division of single cell produce FOUR GAMETES

germ cells to gametes

diploid germ cells to haploid gametes

206
Q

meiosis differences from mitosis

A

meiosis cell division TWICE

takes place in gonads (testes males, and ovaries females)

207
Q

interphase of meiosis

A

same as interphase for mitosis

spermatogonia (precursor to sperm cell)
ova cells
1) Increase in cell size
2) Duplication of organelles
3) Replication of DNA

208
Q

PMAT for meiosis (Prophase)

A

major difference b/w mitosis and meiosis:

HOMOLOGOUS chromosomes join to form TETRAD

209
Q

tetrad and crossing over of chromosomes

A

“cross over” to exchange genetic materials

crossing over creates genotypic diversity (GENETIC DIVERSITY)

210
Q

Prophase (Continued)

A

same as mitosis:
nuclear envelope break
centrosome move
mitotic spindles

211
Q

metaphase

A

only difference is that TETRADS (not single chromosomes) line up

same:
on metaphase plate

212
Q

anaphase (meiosis)

A

sister chromatids stay together in meiosis

(mitosis, sister chromatids pulled apart)

213
Q

telophase + cytokinesis

A

results in 2 gametes with haploid chromosome (1n = 23)

have 23 chromosomes, but each have sister chromatid (?)

46 chromatids total –> 23 chromosomes

1/2 chromosome from each parent

in mitosis –> 46 chromatids total –> 46 chromosomes (single chromatid)

214
Q

meiosis 2

A

two haploid daughter cells enter meiosis 2

215
Q

meiosis 2 PMAT

A

same prophase, but no TETRADS –> I.e. same as mitosis (?)

METAPHASE 2 – same as mitosis (?)

ANAPHASE – same as mitosis –> sister chromatids split

TELOPHASE –> same as mitosis

result = 4 gametes (23 chromosomes each, 23 chromatids)

4 gametes similar but not identical

216
Q

stem cells called germ cells

A

born with many stem cells (called GERM cells)

they undergo MEIOSIS and form GAMETES

217
Q

what are the germ cells?

A

SPERMATOGONIA

OOGONIA

precursors to ova and sperm

218
Q

spermatogonia and oogonia, diploid or haploid?

A

diploid

219
Q

spermatocytes and primary oocytes

A

spermatogonia and oogonia create PRIMARY SPERMATOCYTES,
and PRIMARY OOCYTES

via…
many rounds of MITOSIS

these primary cells become sperm and ova via MEIOSIS

220
Q

spermatogonia –> Primary spermatocyte –> secondary spermatocyte –> spermatid –> mature sperm cell

oogonia –> primary oocyte –> secondary oocyte –> mature ovum

A
221
Q

how do primary spermatocytes become sperm cells?

A

males at puberty –> increase in T

primary spermatocytes enter MEIOSIS 1 & 2

results in SPERMATIDS

222
Q

SPERMIOGENESIS

SPERMATOZOA

A

spermatid becomes spermatozoa via SPERMIOGENESIS

223
Q

Oogenesis

A

In females, mitosis of the oogonium is complete prior to birth
Limited supply of primary oocytes
About 2 million at birth, 400,000 by puberty

The primary oocyte begins meiosis I in fetal development but it is arrested here until puberty

Each month, 6-20 primary oocytes complete meiosis I and enter meiosis II

These cells (usually only one) will finish meiosis II when and only if it is fertilized

224
Q

terms

A

While we are on the topic of gametes, let’s add in a few more terms that will pop up over the next few terms

Gamete: sperm or ovum with with 23 chromosomes

Zygote: is the union of 2 gametes (now 46 chromosomes)

Blastocyst: The zygote will divide into 8 celled blastocyst that implants into the uterine wall

Semester 2 (14 decks)

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