Bio Exam 3 (CH. 10, 11, 12, 13, 46)

photosynthesis

converts sunlight energy to chemical energy stored in sugars

overall photosynthesis equation

6CO2 + 6H20 + Light E → C6H12O6 + 6O2

location of photosynthesis

chloroplasts

Stroma

dense fluid surrounding thylakoid membrane

thylakoid

membranous sacs suspended within stroma; chlorophyll

Photosynthesis stages

light reactions and calvin cycle

location of light reactions

thylakoid membranes

light reactions

convert light energy to chemical energy of ATP and NADPH splits H2O releasing O2

location of Calvin cycle

stroma

calvin cycle (light independent reactions)

uses ATP and NADPH to convert CO2 to G3P (sugar) return ADP, Pi, and NADP+ to light reactions

photosystem

reaction center complex + light-harvesting complexes

photosystem II

functions 1st in light reactions

chlorophyll a P680

photosystem I

functions 2nd in light reactions

chlorophyll a P700

H2O split → releasing O2

flow of light reactions

linear electron flow

calvin cycle

anabolic; builds carbs from smaller molecules and consume energy

spends ATP as energy and consumes NADPH as releasing power

carbon fixation

each CO2 attached to RuBP (5c sugar) → 3 phosphoglycerate

2 formed per CO2 fixed

1st step is catalyzed by rubisco

reduction

each 3-phosphoglycerate receives P group from ATP forming 1,3 - biphosphoglycerate

electron pair from NADH reduces 1,3-biphosphoglycerate → G3P only 1 G3P is net carbohydrate gain

regeneration of RuBP

5 G3P rearranged into 3 RuBP

G3P net synthesis

9 ATP + 6 NADPH

Number of cell signaling stagses

3 stages

signal reception

target cell detects extracellular signaling molecules (ligand/L) via receptor binding

signal transduction

ligand binds receptor → changes receptor → initiates transduction → converts to form that can elicit specific cellular response

cellular response

transduced signal triggers specific cellular response (ex. cytoskeleton rearrangement, gene activation)

cell surface (transmembrane) receptor

plasma membrane proteins

water soluble signals

ex: epinephrine, growth factor

intracellular repcetor

nucleus or cytoplasm

hydrophobic or small molecules

ex: steroid + thyroid hormones, nitric oxide

1st step of G protein-coupled receptor

inactive receptor…. G protein has GDP attached to it…. enzyme is inactive

2nd step of G protein-coupled receptor

active…. ligand binds ro recievor via outside of cell…. G protein binds to cytoplasmic side of the receptor…. GTP reduces GDP

3rd step of G protein-coupled receptor

active G protein dissociates from receptor (ligand not present anymore)…. G protein travels to enzyme and binds to cytoplasmic side of enzyme…. enzyme activated and changes shape….. initiates a cellular response

4th step of G protein-coupled receptor

inactive again….. G protein releases from enzyme and becomes GTPase…. GTP turns into GDP plus an inorganic phosphate….. available for use again once ligand is present

1st step of receptor tyrosine kinase

ligand binds receptor → monomers associate forming dimer

2nd step of receptor tyrosine kinase

dimerization activate tyrosine kinase → add P from ATP to tyrosine on intercellular tail → forms phosphorylated dimer → active

3rd step of receptor tyrosine kinase

intercellular relay proteins bind specific phosphorylated tyrosine → change shape of relay protein → trigger signal transduction → cellular response

receptor tyrosine kinase

protein kinase catalyzes transfer to P group from ATP to tyrosine

1st step of intracellular receptor

hormone diffuses across plasma membrane

2nd step of intracellular receptor

hormone binds receptor → activating receptor

3rd step of intracellular receptor

hormone receptor complex enters nucleus

4th step of intracellular receptor

hormone receptor complex binds specific gene → transcription factor

5th step of intracellular receptor

transcription initiated → mRNA

6th step of intracellular receptor

mRNA transported to cytoplasm → translated into protein

second messenger

cAMP

1st step of making cAMP

adenyl cyclase removes 2 phosphate groups from ATP

2nd step of making cAMP

remaining phosphate attached at 3’ and 5’ carbons → cAMP

inactive cAMP

phosphodiesterase converts cAMP to AMP

PDE catalyzes hydrolysis of 3’ phosphate bond to generate 5’ AMP

binary fission

prokaryotic division

1. bacterium

2. chromosome replicated

3. cell elongates

4. plasma membrane pinched inwards, new cell wall

   1. 2 daughter cells

omnis cellula e cellula

eukaryotic division

1. parent cell

2. DNA copied

3. cell divides

4. 2 identical daughter cells

interphase / G0

cell spends 90% of time here

non dividing state

G1 phase

metabolic activity and growth, make proteins and organelles

contains ½ the DNA

S phase

metabolic activity, growth, and DNA synthesis

G2 phase

metabolic activity, growth, and preparation for cell division

Mitotic (M) phase

equal separation of DNA into daughter cells

10% of cell’s time spent here

G2 of interphase

contains centrosomes, chromosomes (duplicated, uncondensed), nucleolus, nulcear envelope, plasma membrane
DNA has been replicated

no visible chromosomes

cell has not divided

Prophase

contains: early mitotic spindle, aster, centromere, two sister chromatids of one chromosome

Nucleolus disappears

mitotic spindle begins forming

chromatin condenses → chromosomes

centromeres move away from each other

prometephase

contains: fragments of nuclear envelope, nonkinetochore microtubules, kinetochore, kinetochore microtubules spindle MTs

nuclear envelope breaks down

spindle MTs attach to kinetochore → kinetochore MTs

metaphase

contains: spindle, centrosome at one spindle pole, metaphase plate

chromosomes align at equator / metaphase plate

centrosomes at opposite poles

what moves the chromosomes during metaphase

centrosome

anaphase

contains: daughter chromosomes

cohesin proteins cleaved - sister separates

sister chromatids pulled to opposite poles

chromatids → become chromosomes

cell elongates → MTs lengthen

telophase and cytokinesis

contains: cleavage furrow, nucleolus forming, nuclear envelope forming

nucleolus reappears

nuclear envelope reforms

chromosomes decondense

spindle MTs depolymerize

cytokinesis

division of the cytoplasm

what cause the cleavage furrow to form

microfilaments

difference between animal and plant cell in cytokinesis

animal: cleavage furrow

plant cell: creates new cell wall

G1 checklist

no DNA damage, sufficient resources

S checklist

no replication errors

G2 checklist

no DNA damage, chromosome set complete, enough cell components

M checklist

all sisters attached to mitotic spindle on both sides

what happens if the checkpoints fail

cell is killed

growth factor

molecules that promote or inhibit mitosis affect differentiation

EGF receptor (cell cycle promotion)

signal transduction, cell proliferation signal, gene regulation, cell proliferation signal, cell survival

TGF-B receptor (cell cycle inhibition)

signal transduction, gene regulation, antiproliferation signal, programmed cell death

cancer-critical genes

mutation contributes to causation of cancer

proto-oncogenes

stimulating proteins

ex. CDK’s

tumor supressor genes

inhibiting proteins

ex. P53, Rb

proliferation

a tumor begins when a cell starts proliferating because of mutations in the genes that control the cell cycle

tumor formation

rapid multiplication of cells establishes a benign tumor, which can grow larger if it recruits a blood supply

invasion

tumor cells that start invading other tissues are cancer cells

cancer cell characteristics

1. not inhibited by contact

2. not anchorage dependent

3. changes in cell shape

4. changes in nucleus

5. cell population “chaotic”

6. divide indefinitely - “immortal”

what part of the eukaryotic cell does Taxol affect?

microtubules

why is Taxol a good anticancer drug?

stops cell division, causing cell death

asexual reproduction

reproduction with no fusion of gametes

one parent produces → genetically identical

sexual reproduction

reproduction with fusion of gametes

2 parents give life to offspring → genetic variation

karyotype

chromosome array by size and shape

somatic cell

all cells of body except gametes

gamete

sperm cell or oocyte

diploid (2n)

2 sets of chromosomes

human karyotyoe

46 chromosomes : 23 pairs

maternal and paternal homolog

how can you tell if a chromosome is homologous

length, staining, centromere, inherited traits

autosomes

chromosome that is not a sex chromosome

female

XX chromosomes

Male

XY chromosomes

humans

2n = 46

diploid parent cells

ovaries / testes

haploid parent cells

egg / sperm

haploid (n)

1 set of chromosomes

meiosis I

reduction division

prophase I

nuclear envelope breakdown

centrosome movement and spindle formation

chromosomes condense

tetrad

tetrad

four chromatids in homologous pair

metaphase I

tetrads align at equator

anaphase I

homologs pulled to opposite poles

telophase I and cytokinesis

daughters have chromosomes

cytokinesis

2 daughter cells

cytokinesis

division of cytoplasm

interkinesis

pause between meiotic divisions with no S phase