BIOL 1001 LSU Exam 3 Chs 7,8,9 Crousillac

light-dependent reaction

happens ONLY in daytime, occurs in thylakoid membrane b/c that's where chlorophyll is located,

oxygen released as by-product

H2O + NADP+ + ADP => O2 + NADPH + ATP

what is required for the light dependent reaction?

water and sunlight

flow of electrons in light dependent reaction

water → PS2 → PS1 → NADP

products of light dependent reaction

ATP & NADPH

light-independent reaction (Calvin Cycle)

happens 24/7 and occurs in the stroma

CO2 + ATP + NADPH + H2O => C6H12O6 + ADP + NADP+

inputs of light-independent reaction

CO2, ATP, NADPH

output of light-independent reaction

glucose

photosynthesis

transforms light energy trapped by chloroplasts into chemical bond energy and stores that energy in sugar and other organic molecules

what type of chemical reaction is photosynthesis

endergonic

stomata

tiny holes that allow water & CO2 to enter the leaf

vascular bundle

like a vein for a leaf, carries water and sugar throughout the plant

mesophyll cells

found in the middle of the leaf, contain chloroplasts

cuticle

waxy layer surrounding the leaf that seals water in

the shorter the wavelength....

the higher the energy

chemiosmosis

In the thylakoid, as electrons move down the electron transport chain, protons (H+) are pumped, against their concentration gradient, to one side of the thylakoid membrane. As they diffuse to the other side, they activate an enzyme called ATP synthase that is used to make ATP.

energy released from electrons in ETC used to actively transport protons into thylakoid, builds gradient

site of photosynthesis

chloroplasts

chlorophyll

green pigment that gives a leaf its color

responsible for the absorption of the light energy that drives photosynthesis

located in thylakoid membrane

thylakoid

flattened membranous sac inside the chloroplast

stroma

fluid-filled space outside the thylakoids within the chloroplast

accessory pigments

carotenoids and phycocyanins

pigments

substances that absorb visible light

photosystems

assemblies which turn light energy into chemical energy in the thylakoid membranes

What is the purpose of having two photosystems in the light-dependent reactions?

The two generate different energy carriers

When less water is available during a drought, why is the rate of photosynthesis in plants reduced?

Fewer electrons are around to fuel the ETC

chemiosmosis: ATP synthesis

keeps H+ concentration high inside thylakoid, diffuses out to make ATP

what step is most important in the Calvin Cycle?

step 1: carbon fixation

steps of the Calvin Cycle (light-independent)

1. Carbon fixation: acquiring Carbon from the atmosphere and incorporating it into a larger organic molecule. RuBP is converted to PGA.

2. PGA is made into G3P. Energy from NADPH and ATP (from the light-dependent reaction) is used.

3. 2 G3P molecules are made into glucose. The remaining G3P molecules are made back into RuBP. Requires ATP energy.

RuBP SOAKS UP CO2, CONVERTS TO PGA

PGA CONVERTS TO G3P, ELECTRONS AND ATP USED

REST OF G3P MAKES MORE RuGP

In the Calvin cycle, where do the carbons used to synthesize glucose originate?

CO2

How are the light-dependent reactions and the Calvin cycle related?

The energy-carrier molecules of the light- dependent reactions fuel the Calvin cycle.

What is responsible for the beautiful shades of red, orange, and gold in autumn leaves?

Accessory pigments become visible after chlorophyll breaks down.

where does glycolysis occur?

cytoplasm

is oxygen required for glycolysis?

NO

inputs of glycolysis

1 glucose molecule

outputs of glycolysis

2 pyruvates(pyruvic acid)

2 NADH molecules

2 net ATPs

fermentation

happens when there is not enough oxygen to completely breakdown glucose through cellular respiration; glucose is partially broken down by glycolysis & occurs to regenerate NAD needed for glycolysis, so 2 ATPs can be made every time glycolysis occurs

anaerobic (without O2)

NO ATP production

partial degradation of sugars; regenerates NAD+

mitochondria

POWERHOUSE OF THE CELL

produces ATP

3 metabolic stages of cellular respiration

1. Glycolysis

2. Krebs cycle (Citric Acid Cycle)

3. ETC & oxidative phosphorylation

Glycolysis

harvests chemical energy by breaking down glucose to pyruvate

catabolic pathway during which 6-carbon glucose split into two 3-carbon sugars, then rearranged by stepwise process that produces 2 pyruvic acid molecules

occurs in cytoplasm

occurs w/ or w/out O2

net result is 2 ATP and 2 NADH

2 phases of glycolysis

1. glucose activation

2. energy harvest

glucose activation

uses cellular ATP to phosphorylate (adds a phosphate group to) the glycolysis intermediates

costs 2 ATP per glucose

energy harvest

produces ATP

yields 4 ATP molecules per glucose

2 molecules of NADH per glucose

Glycolysis is distinct from cellular respiration because...

Glycolysis does not occur in the mitochondria

two types of fermentation/2 common products of pyruvate acid

ethanol/alcohol

lactic acid

alcoholic fermentation

lactic fermentation

How can glycolysis continue producing energy when oxygen is not present?

Fermentation regenerates the NAD+ needed for glycolysis by allowing pyruvate to accept electrons and H+ from NADH

You help a friend move, and the next day, your arms and legs are sore. What caused the soreness?

Your overworked muscles did not get enough O2 and switched to fermentation, which builds up lactate

bridge reaction

connects glycolysis to the Krebs cycle, converts pyruvic acid to acetyl CoA

steps of bridge reaction

1. removal of CO2

2. Production of NADH from NAD+;

two molecules of NADH per glucose molecule

3. attachment of a coenzyme A to form acetyl CoA

Kreb's Cycle

occurs in mitochondrial matrix (innermost part of mitochondria)

completes the breakdown of glucose

for every molecule of glucose entering glycolysis, 2 pyruvates enter Krebs Cycle

**has to turn twice to breakdown 1 molecule

Electron Transport System

located in inner mitochondrial membrane

accepts energy as electrons from NADH & FADH2

uses energy to make ATP by oxidative phosphorylation

produces most of the ATP of cellular respiration

**does NOT actually produce ATP, just maintains proton gradient

products of Krebs Cycle

NADH, FADH2, small amount of ATP

steps of Electron Transport Chain

1. Electrons pass through series of enzymes & other proteins (ETC)

2. Their energy is used to pump H+ from the matrix into intermembrane compartment, creates a gradient

chemiosmosis (ATP synthesis)

coupling of exergonic electron flow down an ETC to endergonic ATP production by the creatiohn of a proton gradient across a membrane

occurs in inner mitochondrial membrane

overall summary of glycolysis, Krebs cycle & ETC

C6H12O6 + 36ADP + 6O2 →

6CO2 + 36ATP +42H2O

input of bridge reaction

2 pyruvates produced from glycolysis

outputs of bridge reaction

2 NADH & 2 acetyl CoA molecules

inputs of Krebs Cycle

2 acetyl CoA molecules produced during bridge reaction

outputs of Krebs Cycle

(2 turns)

6 NADH

2 FADH2

2 ATPs

inputs of chemiosmosis/ETC

electrons carried by NADH & FADH2

outputs of chemiosmosis/ETC

32-34 ATP, water

why is oxygen important in chemiosmosis/ETC

ultimate acceptor of electrons, if no oxygen present, no ATP gets made

role of ATP synthase

protons diffusing back into the matrix activate ATP synthase enzyme, & produce ATP in the process

cellular reproduction/cell division

process in which genetic info of a cell is passed along to the next generation of cells

involves division of a parent cell into 2 daughter cells

replication of DNA

equal distribution of DNA to opposite ends of dividing cell

separation into 2 daughter cells

interphase

period of cell cycle when cell is not dividing

90% of cell cycle

high metabolic activity

chromosomes & organelles are duplicated

steps of interphase

G1: cell growth and differentiation

S: synthesis of DNA, chromosomes duplicated

produces sister chromatids

G2: cell growth

mitosis

division of the nucleus

DNA is equally distributed into 2 daughter nuclei

cytokinesis

division of cytoplasm that forms 2 separate daughter cells, each containing a single nucleus

chromosomes

threadlike structures composed of chromatin (DNA & proteins)

breakdown of genome

genome → chromosomes → chromatin → DNA + proteins

DNA replication

2 chromosomes attached at centromere called sister chromatids

-produces replicated chromosome w/ 2 identical sister chromatids

sister chromatids

separate during mitosis, each forms individual chromosome

karyotype

pairs of chromosomes arranged by size, shape and staining pattern

homologous chromosomes

pair of chromosomes that contain the same genes; have same size, centromere position and staining pattern

NOT the same as replicated chromosomes

one is from mother, one is from father

human cells contain how many chromosomes?

46 chromosomes/23 pairs of homologous chromosomes

autosomes

non-sex chromosomes

22 pairs in cells

haploid

cells contain one set of chromosomes, only found in gametes

gametes

haploid egg/sperm cells & contain half # of chromosomes as ordinary cells

zygote

2 haploid gametes unite during fertilization

fertilized egg

mitosis

nuclear division

5 phases: early & late prophase, metaphase, anapahse, telophase

spindle apparatus

part of cytoskeleton

separates chromosomes into daughter cells

early prophase

step 1 of mitosis

chromatin condenses

spindle apparatus forms

kinetochores

protein structures on chromosomes where spindle fibers attach during mitosis

late prophase

step 2 of mitosis

nuclear envelope disappears

microtubules attach to kinetochore

polar microtubules radiate towards cell's equator, each microtubule attaches to separate sister chromatid

metaphase

step 3 of mitosis

chromosomes move to & align on the equator of the cell

anaphase

step 4 of mitosis

sister chromatids divide into separate daughter chromosomes & move toward opposite poles

movement of chromosome is accomplished by depolymerization of microtubules at kinetochore (break apart)

cell begins to elongate b/c polar microtubules slide past each other & push poles apart

telophase

step 5 of mitosis

daughter chromosomes arrive at poles

kinetochore microtubules diappear

polar microtubules elongate, helps causes the formation of the cleavage furrow

daughter nuclear envelopes form

chromatin begins de-condensing

asexual reproduction

one parent

single parent passes ALL genes

rare genetic differences are result of mutations

sexual reproduction

two parents each pass half of their genes

greater genetic variation w/ offspring being genetically different from parents & siblings

meiosis

occurs in ovaries and testes

meiotic division followed by 2 rounds of cytokinesis to produce 4 daughter cells that become gametes

meiosis II

separates sister chromatids & puts on chromatid into each daughter nuclei

meiosis I

homologous chromosomes pair up

sister chromatids linked at centromere, non-sister chromatids linked at chiasmata

exchange of genetic info btw un-identical chromosomes

meiosis 1: prophase 1

chromosomes condense and pair up,

sister linked at centromere, non-sister linked at chiasmata

genetic crossing over

nuclear envelope disappears

chiasmata

regions of paired homologous chromosomes where chromatids have exchanged genetic material b/c crossing over

meiosis I: metaphase I

chromosome pairs align at equator

kinetochores face same pole

centromeres of homologous face opposite poles

meiosis 1: anaphase 1

spindle microtubules interact w/ kinetochore fibers

homologous chromosomes move toward opposite poles

sister chromatids remain attached

meiosis 1: telophase 1 and cytokinesis

chromosomes arrive at poles

cell divides

meiosis II final result

prophase II, metaphase II, anaphase II, telophase II

cell division occurs creating four haploid daughter cells

difference btw mitosis and cytokinesis

mitosis is division of the nucleus

cytokinesis is actual division/division of the cytoplasm