Lecture midterm #2 Flashcards
1
Q
What is the process called when plants grow toward the light?
A
Phototropism
2
Q
What are the two major classes of light receptors and what do they do?
A
1) Blue-light photo receptors: Control Hypocotyl (stem) elongation, stomatal opening, and phototropism.
2) Phytochromes: regulate seed germination and shade avoidance.
3
Q
What are the 2 photoreversible states that Phytochromes live in?
A
Pr
Pfr
4
Q
How to Phytochromes trigger germination?
A
Red light (sunlight) triggers conversion of Pr to Pfr (happens throughout daytime and stimulates germination)
Far-red light triggers conversion of Pfr to Pr (happens overnight and INHIBITS germination response)
5
Q
What type of light do leaves in the shade absorb?
A
They absorb more FAR-RED light than red light.
which shifts the phytochrome ratio to (Pr> Pfr)
**this shifts the growth patter to growing taller INSTEAD of branching out (allows it to find more light)
6
Q
How to phytochromes detect sunlight?
A
at sunlight Pfr levels start to increase
*way plants can detect day time (morning)
at night there is a shift from Pfr to Pr. then morning hits and they reverse back
7
Q
What are photoperiods?
A
Length of Dark/ Light cycle
*primary environmental stimuli plants used to detect the time of year
8
Q
What is photoperiodism?
A
The response plants have to seasonal changes (day length) within the day to adapt to the seasonal changes in their environment
9
Q
What are short day plants?
A
Flowers with a set minimum number of hours of darkness
short day (Long night)
*require long periods of darkness
10
Q
What are long day plants?
A
Flowers with a set minimum number of hours of light.
*require long periods of light
11
Q
What are day-neutral plants?
A
Controlled by plant maturity (not photoperiod)
12
Q
What is a plants response to gravity called?
A
Gravitropism
Roots show (+) gravitropism (they grow DOWN)
Shoots show (-) gravitropism (they grow UP)
13
Q
What is a plants response to touch called?
A
Thigmotropism
Occurs in vines and other climbing plants
14
Q
What is the morphological adaptation some plants have to grow in the dark called?
A
Etiolation
Pale shoots with no leaves and a few short roots
If exposed to light it will go through DE ETIOLATION and will grow normally
15
Q
What are the 3 stages of Signal Transduction Pathways?
A
1) Reception: detected by receptors (proteins)
2) Transduction: Transfer and amplify signals from receptors to responders
3) Response: Change in regulation of cell activities (usually increased by enzyme activity)
16
Q
Potatoes response to being introduced to light?
A
De etiolation
Reception: Phytochrome stimulated by light
Transduction: Phytochrome opens Ca2+ channels and activated enzyme that makes cGMP.
Response: protein (kinases) (enzyme) is activated, transcription factors up-regulate gene transcription involved in photosynthesis
17
Q
What are the 5 growth promoters of plant hormones?
A
1) Auxin
2) Gibberellins
3) Cytokinins
4) Strigolactones
5) Brassinosteroids (dont need to know this one)
Ass Good Cake Sticky Balls
18
Q
What are the 3 growth inhibitors of plant hormones?
A
1) Ethylene
2) Abscisic acid (ABA)
3) Jasmonates
Every Ass Jiggles
19
Q
Tell me about Auxin?
A
- Plant growth promoter hormone
- chemical involved in stem and cell elongation
- Produced mostly in shoot tips (apical meristem) and leads to Phototropism
- Auxin moves to the shaded part of the stem which causes elongation of that side and movement toward the light
20
Q
What are expansins?
A
- Enzymes that loosen the fabric of the cell wall (with cellulose loosened the plant can elongate)
- Auxin stimulates proton pumps (H+) in plasma membrane
- Proton pumps lower pH in cell wall and activated expansins
21
Q
How does Auxin work in branch growth?
A
Reduced Auxin in one branch promotes growth in another. (spacial organization)
growth of new branches is due to high auxin concentration in that area
22
Q
What is phyllotaxy?
A
Arrangement of leaves on stems
23
Q
What is Auxin IBA?
A
Auxin Indolebutyric Acid
Stimulates “Adventitious roots” = arise from an area on the plant that is not the roots
*used for gardening and farming
24
Q
What does Gibberellins (GA) do?
A
Hormone that promotes plant elongation in the internodes, fruit growth and see germination.
Produced in young roots and leaves and causes “bolting”= rapid growth of a plant
25
What are Jasmonates and what do they do?
Plant hormone that aids in defense.
(eg) Caterpillar bites leaf, the chemicals in the caterpillars saliva stimulates the signal transduction pathway, synthesis and the release of volatile attractants (sends a signal that recruits parasitoid wasps to come and lay their eggs in the caterpillar)
fucking savage
Also tissue healing and fruit ripening
26
How does fruit ripen?
Burst of ethylene production in fruits triggers ripening.
ethylene triggers ripening, ripening triggers more release of eythene (positive feedback)
27
How does ethylene respond to mechanical stress?
Triple response:
SLOWING of stem elongation
THICKENING of stem
HORIZONTAL growth
*allows growing shoot to push through/ around obstacles
28
What is Ethylene?
A plant hormone produced in response to stressed.
1) Mechanical strengthening
2) Fruit ripening
3) Leaf abscission (dropping)
4) Aging/ senescence (death)
29
What is apoptosis?
Programmed cell death
A burst of ethylene is associated with apopsis
30
What are the 2 main effects of Abscisic acid (ABA)?
1) Seed dormancy: ensures that sees will only germinate in optimal conditions
2) Drought tolerance: enables plants to withstand a drought
31
What are brassinosteroids?
(dont need to know this one for the lecture exam)
Plant hormone that induce cell elongation AND cell division in stems
Also slow down leaf abscission (dropping)
32
What are strigolactones?
Plant hormone that aids in Auxins inhibition of bud growth, stimulates seed germination, and helps establish "Micorrhizal associations"..
COME BACK TO THIS ONE
33
What are Cytokinins?
Plant hormone that stimulate cytokinesis (cell division).
Produced in roots shoots and fruits
Works with Auxin to control cell division and differentiation (roots vs shoots)
34
What is Apical Dominance?
(dont need to know this one for the lecture exam)
Come back to this one
35
What are the anti-aging effects of cytokinins?
- Inhibit protein breakdown
- Stimulate RNA and protein synthesis
- Mobilizing nutrients from surrounding tissues
**florists use cytokinins on flowers to keep them fresh
36
How do Gibberellins promote seed germination?
- After water is absorbed Gibberellins are released from the embryo and that signals the seed to germinate.
- GA signals to outer layer of endosperm
- Amylaze hydrolyze starch
- Cotyledon uses sugars for growth
37
What are the 2 major types of proteins in a plasma membrane?
1) Peripheral proteins: sit on one side of the membrane.(few hydrophobic amino acids) AID IN SIGNAL TRANSDUCTION
2) Integral proteins: sit within the membrane. (hydrophobic/phylic amino acids) HELP HYDROPHYLIC PARTICLES TRAVEL THROUGH THE MEMBRANE
38
What are the functions of integral proteins in the phospholipid bilayer?
1) Transport: of materials across the hydrophobic core (channels, carriers, pumps)
2) Enzymatic activity: ATP synthase
3) Signal transduction: Phytochome
4) Cell to cell recognition: (immune cells)
5) Joining cells together: (tight junctions)
6) Attachment to cytoskeleton and extracellular matrix (collagen)
39
What dos fluid refer to in the plasma membrane?
"lateral movement" on the membrane (10 to the 7 times per second)
"flip-flop" phospholipids might transversely flip across the membrane (rare)
40
What changes the mobility of the plasma membrane?
-Cool temperatures turn the fluid state to a solid (gel state)
- Membranes rich in saturated fatty acids are stiff. membranes with unsaturated fatty acids are more fluid because of the kinks (dbl C bonds)
-Cholesterol (if its cool it keeps it from getting too rigid, if too warm it keeps it stabilized so it doesn't become too fluid)
41
What is diffusion and passive transport?
- the movement of particles DOWN their concentration gradient until equilibrium
- Passive transport is transport that DOES NOT require ATP
42
The plasma membrane exhibits "selective permeability". What can pass through easily and what needs help?
Easily: Hydrophobic NONpolar substances (fatty acids, steroids, gasses like O2 and CO2)
Needs help: Hydrophilic POLAR substances (ions, sugars, amino acids,
43
Water diffuses from regions of __________ to ___________.
Low solute concentration (high water concentration)
to High solute concentration (low water concentration)
**passively
44
What is tonicity?
The ability of a surrounding solution to cause a cell to lose of gain water.
45
What are isotonic solutions?
Have the same solute concentration of that of the inside of the cell
46
What is a hypertonic solution?
Have a higher solute concentration than the inside of the cell.
*cell loses water
47
What is a hypotonic solution?
Have a lower solute concentration than that of the inside of the cell.
*cell gains water
48
What is osmoregulation?
The control of water balance
49
How do hyrdrophilic particles move through the plasma membrane?
Facilitated diffusion (No ATP) passive
Carrier proteins (provide corridor)
Protein channels (change shape to translocate particles)
50
WHY is active transport a thing?
Because cells sometimes need particles to go UP their concentration gradient.
51
What is a membrane potential?
Voltage differences across membrane
**acts a stored energy to that can be used for cellular work
52
What is an electrogenic pump?
Proteins that generate voltage differences
(eg) Proton pump for plants, fungi and bacteria.
(eg) Na+/ K+ pump for animals
53
What is cotransport?
Active transport (REQUIRES ATP)
A carrier protein that allows the transport of two different things (solute and an ion) from one side of the membrane to the other at the same time
54
What is bulk transport?
Active transport (REQUIRES ATP)
The movement of larger molecules or solutions in or out of a cell
55
What is exocytosis?
Active transport (REQUIRES ATP)
Transport vesicles containing cargo migrate over to the membrane, fuse, and release contents.
56
What is endocytosis?
Active transport (REQUIRES ATP)
Cells take IN particles by forming vesicles derived from the plasma membrane
57
What is phagocytosis?
Active transport (REQUIRES ATP)
Endocytosis of large particles
(means Cell eating)
Cells engulf particles in a phagocytic vacuole.
Used by protists and a means of getting food
58
What is pinocytosis?
Active transport (REQUIRES ATP)
Endocytosis for small particles
(means Cell drinking)
Cells constantly undergo small invaginations (folds inwards)
Take in fluid containing solutes and pinch off to form a vesicle around it
59
What are ligands?
Receptor mediated endocytosis
Active transport (REQUIRES ATP)
A molecule that irreversibly binds to a receiving membrane surface protein (receptors).
Receptor-ligand interaction triggers vesicle formation and internalization.
60
How do cells most often communicate with eachother?
Chemical signals at their exteriors (cell walls, ECM, junctions)
61
How do plant cells communicate to one another?
Plasmodesmata
Channels between adjacent plant cells that allow for chemicals to pass
**Plants need this because cell walls are thick (multilayered cellulose/ protein walls)
62
How do animal cells communicate with one another?
Extracellular matrix ECM
Protein fibers and proteoglycan complexes of the ECM
Intercellular juncions (Tight, gap, desmosomes)
63
What are the 3 types of intercellular junctions?
1) Tight junctions
2) Desmosomes
3) GAP junctions
64
What are tight junctions?
Animal cells use them to prevent leaks
Neighbouring cell membranes are pressed together (like a quilt stitched together)
FUNCTION: Prevents fluids from leaking between cells
65
What are desmosomes?
Animal cells use these to anchor to one another
Fasten cells together (like a spot weld)
FUNCTION: Join cells together in strong sheets
66
What are GAP junctions?
Animal cells use them to communicate
FUNCTION: Provide cytoplasic communication via connexons (little clips with a pore in them)
67
What are integrins?
Membrane proteins (surface molecules) that have direct contact with one another
Cell to cell recognition
Chemical messengers that travel short distances.
*Local signalling
68
How do cells undergo Local signalling?
Integrins
Membrane proteins that have direct contact with one another (cell to cell recognition)
Chemical messengers that travel short distances.
69
How do cells undergo long distance signalling?
Hormones
"Endocrine signalling"
**in order for a cell to respond it needs a specific receptor
70
What are the 3 main types of membrane receptors?
1) G protein-coupled receptors
2) Receptor tyrosine kinases
3) Ion channel receptors
71
What are G protein-coupled receptors?
1 of the 3 main types of membrane receptors
- Bing with GTP (like ATP) acts like an on/off switch
* if receptor is inactive then GDP is bound to the G protein
** if receptor is active (ligand binds), receptor binds to G protein and GTP replaces GDP (now G protien is active)
***active G protein binds to nearby enzyme -> cellular responses
72
What are Receptor Tyrosine kinases (RTKs)?
1 of the 3 types of membrane receptors
- Receptors that attach phosphates to tyrosines
- Can trigger multiple signal transduction pathways at once
73
What are ion channel receptors?
1 of the 3 types of membrane receptors
- Ligand-gated channel receptor.
- Acts as a gate and the receptor changes shape.
* once the ligand binds to the receptor the gate allows specific ions to travel through (Na+, Ca2+) and this causes a cellular response
74
What happens during "reception"?
The target cell detects a signalling molecule that binds to the receptor and cell surface.
75
What happens during "transduction"?
Reception of the signal causes the receptor to initiate a signal transduction pathway.
76
What happens during a "response"?
The transduced signal triggers a specific response in a target cell (series of steps)
77
What 3 steps happen when a cells receptor gets a signal?
1) Reception
2) Transduction
3) Response
78
What do Protein kinases (PK) do?
They trandfer phosphate groups from ATP to protein (phosphorylation)
79
What do Protein photophases (PP) do?
They remove the phosphates from proteins (dephosphorylation)
80
What is a "second messenger"?
What are the 2 important second messengers?
A signal might be relayed through a second messenger.
- Small non-protein water soluble molecules or ions
**Cyclic AMP (cAMP)
***Calcium (Ca2+) ions
81
What does cAMP do?
2nd messenger
-Extracellular signals (1st messenger) trigger the formation of cAMP from ATP
- Activates phosphorylation cascade ending in an activation of a protein
(cAMP is synthesized from ADENYLYL CYLASE)
(cAMP can be brooken down by PHOSPHODIESTERASE)
82
What is adenylyl cylase?
Enzyme that synthesizes cAMP (a 2nd messenger)
83
What is phosphodiesterase?
Enzyme that breaks down cAMP (a 2nd messenger)
84
What does an overproduction of cAMP lead to?
Over-secretion of salt
*water enters colon via osmosis (leads to diarrhea and possibly death
(Cholera over-produces cAMP)
85
What is apoptosis?
Programmed cell death
(eg) normal part of finger development
Components of the cell are chopped up and packaged in vesicles that get digested from scavenger cells.
**prevents enzymes from leaking out of a dying cell and damaging neighbouring cells
this is cool
86
Cell theory
Every cell came from a cell
87
What is cell division?
A cell splitting into 2.
*before dividing a cell must duplicate is DNA
why did I even make a fucking card for this
88
What is a cell cycle?
Charts the progress of a cells lifespan from its formation to its division
89
How to prokaryotes reproduce?
Binary fission
Asexual reproduction
Circular chromosome replicates and the two daughter chromosomes actively move apart.
plasma membrane pinches inwards, dividing the new cells.
New daughter cells are identical
90
In Eukaryotes how is DNP packaged?
Chromosomes: Long dense LINEAR strands
91
What is a duplicated chromosome?
2 sister chromatids (joined copies of the original chromosome)
Held together by a centromere
92
What are they called when sister chromatids get separated into new nuclei?
Daughter chromosomes
93
What are the 2 phases of a cell cycle?
1) Interphase: cells grow, chromosomes duplicate (majority of their life)
2) Mitotic (M) phase: cellular division (mitosis and cytokinesis)
94
What are the 3 sub phases of interphase?
1) G1 phase: (1st gap)
2) S phase: (DNA synthesis)
3) G2 phase: (2nd gap)
95
What does interphase look like?
Nucleolus is often visible
DNA condensed in chromatin (foggy)
Cell has 2 centrosomes
96
What are the 5 sub-phases of mitosis?
1) Prophase
2) Prometaphase
3) Metaphase
4) Anaphase
5) Telophase
97
What does early prophase look like?
Nucleolus is no longer visible
Centrosomes move to opposite poles (begin forming mitotic spindle)
Chromosomes condense and become clear strands
98
Whats the mitotic spindle, whats it made of, whats it do?????
Controls chromosome movement during mitosis
made of microtubules
(collectively includes centrosomes, spindle microtubules, and asters)
99
What are kinetochores?
Proteins that connect centromeres (of chromosomes) to microtubules
100
What does late prophase look like?
Nuclear envelope degenerates
Centrosomes extend microtubules and attach the kinetichore to the centromeres of the chromosomes
101
What does metaphase look like?
No nucleus visible
centrosome microtubules form spindle apparatus which is connected to the opposite centrosomes and kinetohores.
Chromosomes line up at the metaphase plate
102
What does anaphase look like?
Sister chromosomes are being pulled apart to their poles. (now called daughter chromosomes)
Centrosomes shorten their kinetochore microtubules (via motor proteins)
Lengthen their non-kinetochore microtubules (to push away from the other pole)
103
During anaphase what pulls the kinetochores closer to their centrosome?
Motor proteins
Microtubules shorten by depolymerizing at their kinetochore end
**this is what pulls the sister chromatids apart
104
Tell me about the non-kinetochores?
From opposite poles they overlap
During anaphase they push apart from eachother
Cause cell to further elongate and separate the daughter chromosomes
105
What does telophase look like?
2 daughter nuclei begin to from.
nucleoli reappear
1 centrosome present in each new cell
Chromosomes decondense in new nuclei
106
In animal cells after telophase how do the cells fully separate?
Cytokinesis
The formation of a "Cleavage furrow"
Ring of actin microfiliments contract, pinching the cell
107
In plants cells after telophase how do the cells fully separate?
Cytokinesis
The formation of a "Cell plate"
Vesicles contain cell wall materials assemble at the metaphase plate
108
What are cytoplasmic signals?
A cell in S phase was fused to a cell in G1 phase and triggered the G1 cell to enter S phase and synthesize DNA
A cell in M phase was fused to a cell in G1 phase and it triggered the G1 cell to undergo mitosis even though is hadn't duplicated its chromosomes yet.
109
What are the 3 most important checkpoints?
G1, G2 and M
110
What does G1 checkpoint do?
If go-ahead signal is recieved the cell will complete S, G2 and M phase.
If go-ahead signal is not recieved the cell will leave the cell cycle and go to G0 (nondividing phase)
111
What are the 2 regulatory proteins in the checkpoints?
Cyclins
Cyclins-dependent kinases (Cdk)
*their activity fluculates: MPF (maturation promoting factor)
112
What does G2 checkpoint do?
Cyclins accumulate at end of S phase, eventually binding with Cdk to from MPF which triggeres the cells passage through G2 phase to the M phase
SIMPLE: go from G2 to M phase
113
What happens to Cdk when mitosis is done?
Gets recycled and is ready to bind cyclin in the next S phase
114
What are the 3 external checkpoint signals?
1) Growth factors: (proteins from other cells)
2) Anchorage dependence: (most animal cells must be attached at a surface)
3) Density-dependent inhibition: (most crowded cells stop dividing)
115
Tell me about abnormal cells?
They ignore all chechpoints and external checkpoint signals.
They form TUMOURS
116
What are benign tumours?
Abnormal cells that remain at the original site.
usually slow growing
117
What are malignant tumours?
Cancer
invade surrounding tissues in the process known as "metastasis"
First spread to adjacent regions
Spread through lymphatic system and blood
118
What is chemotherapy?
Injection of chemicals that target rapidly dividing cells
119
What is radiation therapy?
Radiated the tumour with DNA damaging high energy waves
120
What is immunotherapy?
Boosts the patients immune system to help fight cancers
121
What is asexual reproduction? pros and cons
1 parents produced genetically identical clones.
Pros: Fast, produces many, no need to find mate.
Cons: no genetic variations, population can easily be wiped out, harder to adapt/ evolve.
122
What are some examples of asexual reproduction?
Mitosis
Fragmentation
Budding
Binary fission
Parthenogenesis
Spore formation
123
Tell me about sexual reproduction?
2 parents produce genetically unique offsprings
Both parents produce HAPLOID gametes
Gametes fuse during fertilization and form a ZYGOTE.
Zygote = DIPLOID (2n)
124
How many chromosomes do Haploid gametes have?
1 set of chromosomes (n=23)
125
How many chromosomes do Zygotes and somatic cells have?
not making a card for them but somatic cells = non-reproductive cells
Both sets of parental chromosomes and are diploid (2n=46)
126
What are karyotypes?
Ordered displays of an organisms chromosome pairs.
22 of the chromosome pairs are called AUTOSOMAL HOMOLOGOUS PAIRS (same genes (segments of DNA) and LOCUS (location)
1 set are SEX CHROMOSOMES (XX or XY)
127
What type of sex chromosome comes from an egg?
XX
Thus eggs only donate X to offsprings
128
What type of sex chromosome comes from sperm?
XY
Thus sperm can donate either X or Y to their offsprings
129
Meiosis (simple simple breakdown) what comes out?
2 rounds of meiosis
4 daughter cells
Daughter cells are HAPLOID
Daughter cells are UNIQUE
130
What occurs in interphase of Meiosis?
Homologous pair of chromosomes in diploid parent cell --->
--->homologous pair of replicated chromosomes (sister chromatids)
131
What happens in meiosis 1?
Diploid cells become haploid
Daughter cells are unique
Sister chromatids still connected
Crossing over
132
What happens in meiosis 2?
Haploid cells sister chromtids randomly separate
4 unique haploid daughter cells are fromed
133
What is a tetrad and where does it happen?
group of 4 chromatids
Prophase 1
134
What is a chiasmata and where does it occur?
Each tetrad has them. Its where they recombine (x shape region) (crossing over)
Prophase 1
135
What happens in metaphase 1 of meiosis?
Tetrads line up at metaphase plate
Microtubules and kinetochores attach to1 sister chromatid pair of each tetrad
136
What happens in telophase 1 of meisois?
New nuclei form around each haploid set of chromosomes
Each chromosmes still consist of 2 sister chromatids
Cytokinesis occurs simultaneously forming 2 haploid DAUGHTER CELLS
137
What is the next phase after telpohase 1 of meisois?
INTERKINESIS (centrosomes duplicate but not DNA)
**remember there is no interphase in meiosis 2.
138
What happens in prophase II of meiosis?
Spindle apparatus form between the 2 centrosomes
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139
When does independent assortment happen?
Anaphase I of meiosis
