Biology 3rd Nine Weeks Exam

bioenergetics

study of energy in living systems (environments) and the organisms (plants and animals) that utilize them

metabolism

the sum of all chemical reactions in a living organism. includes: cellular respiration and photosynthesis

enzyme

proteins that catalyze chemical reactions in living thing

characteristics of enzymes

1. needed for all chemical reactions (metabolism)
2. assists in breaking down and building biomolecules
3. most are proteins (end in ase)
4. aren’t used up in reactions; continue to work reactions until they are stopped
5. function depends on structure
6. only certain molecules can bind to enzymes
7. save cellular energy

parts of an enzyme

substrate

active site

enzyme substrate complex

allosteric site

substrate

specific reactant (molecule) that enzymes act on

active sites

place where substrate bind to enzymes

enzyme-substrate complex

when enzyme and substrate join together; induced fit between enzyme and substrate to catalyze reaction

allosteric site

site on enzyme that allows a molecule to start or stop reactions (on/off switch); save cellular energy

causes of enzyme denaturing

* change in pH
* change in temperature
* change in salt balance

what is homeostasis for humans?

* pH=7.4
* temp=98.6
* salt balance= 33ppm

what is non-competitive inhibition?

molecule that binds to allosteric site and causes shape change so the substrate can’t bind with the active site

what is competitive inhibition?

substrates that interfere with active sites so substrates can’t interact with enzymes.

what is allosteric regulation?

regulatory molecules that cause conformational shape changes to enzymes

__2 types:__ inhibitors and activators

inhibitors

molecules that keep enzymes inactive; saves energy if enough product has been made

activators

molecules that keep enzymes active; saves energy because it keeps enzymes producing

what is the “lock and key” fit?

active sites work like a lock and key. a substrate must be a certain shape in order to fit with the enzyme. once an active site causes a conformational shape change the enzyme will catalyze the reaction.

catalysis

enzymes; substance that speed up chemical reactions by decreasing activation energy

characteristics that make enzymes catalysis

1. increase reaction rate
2. aren’t consumes with reaction
3. active site lower activation energy by creating a favorable environments for substrate
4. decrease activation energy

how are enzymes named?

named for the reaction they catalyze; end in “ase” if protein

* amylase
* lactase
* maltase
* sucrase
* lipases

what organisms undergo photosynthesis?

autotrophs

autotroph

self-feeder; makes energy from sunlight (chlorophyll). includes all plants, phytoplankton, algae, mosses, and ferns.

formula for photosynthesis

6CO2 + 6H2O → C6H12O6 + 6O2

formula for cellular respiration

C6H12O6 → 6CO2 + 6H2O + energy

ATP

main energy molecule made during photosynthesis and respiration

how is ATP made?

hydrolysis breaks down ADP causing the covalent bond to break between phosphates which releases large amounts of energy

phosphorylation

when ATP gives a phosphate to another molecule (enzyme) so it can be activated. energy is released by breaking the covalent bond between phosphates

how can the rate of photosynthesis be found in a lab?

* amount of CO2 present


* amount of sunlight
* amount of sugar made
* amount of oxygen produced

how can the rate of cellular respiration be measured in a lab?

* amount of CO2 present


* amount of sugar present
* amount of oxygen comsumed

photons

the energy wavelengths sunlight travels in

what photons are used in photosynthesis?

red (longest wavelenth, least energy) wavelengths and blue (shortest wavelength, most energy) wavelengths

* green light is reflected

what does ROY G BIV stand for?

Red, Orange, Yellow, Green, Blue, Indigo, Violet

absorbed colors are used, reflected colors are not

chlorophyll A

main green pigment in plants; absorbs red light and had magnesium

chlorophyll B

green pigment helps chlorophyll A receive sunlight energy; mainly absorbs blue light

carotenoids

accessory pigments that help chlorophyll and proteins in thylakoid membrane

photosystem

a complex protein made of chlorophylls and proteins in thylakoid membrane

* photosystem II
* photosystem I

PSII

makes ATP and NADPH

PSI

only makes ATP

parts of a chloroplast

* thylakoid
* grana
* lamella
* stroma
* calvin cycle

thylakoid

single disks that contain chlorophyll; photosystems II and I on thylakoid membrane trap sunlight; where light dependent reaction occur

grana

stack of thylakoids; increases surface area for photosynthesis

lamella

connection between grana

stroma

liquid between grana; where carbohydrates are made in calvin cycle

calvin cycle

occurs in stroma; uses ATP and NADPH from light reactions to make sugar

what is the goal of light reactions?

__to make energy molecules that are passed on to the calvin cycle.__

uses light to break water into O2 and H+. light excites the electrons released by water that travel through an electron transport chain to become ATP and NADPH (used in calvin cycle)

what is the goal of the calvin cycle?

__to make sugar and carbon fixation.__

light is not needed; uses the energy molecules made in the light reactions combined with CO2 to make sugar

what two process make up the light reactions?

* non-cyclic electron flow
* cyclic electron flow

non-cyclic electron flow

makes ATP and NADPH; starts and ends in different places (starts: PSII; ends: PSI)

cyclic electron flow

makes ATP; starts and end in PSI using an electron transport chain

step 1 - photosynthesis

* light hits water in stroma, PSII and PSI all at once

\- water splits into O2 (removed by stomata) and H+ then releases electrons

\- PSII is energized by wavelength P680. Mg atoms lose 2 electrons that are collected in a primary collection protein and moved toward PSI with an electron transport chain.

\- PSi is energized by wavelength P700 and Mg loses 2 electrons which are collected in another collection protein and moved to NADH+ along an electron transport chain.

step 2 - photosynthesis

* electrons move down electron transport chain where 2 molecules are enter changing electrons (redox reactions) the molecule giving is oxidized, the molecule getting is reduced. redox reactions are powered by proton pump, concentration gradient drives reaction
* PSII- free electrons move toward PSI using concentration gradient
* PSI- free electron are used to reduce NADP+ to NADPH

step 3 - photosynthesis

trapped H+ ions in thylakoid membrane are released through ATP synthase complex. complex makes ATP by phosphorylation (ATP→ADP)

cytochrome C

a protein found in the inner cell membrane of all mitochondria, chloroplasts and plasma membrane of prokaryotes; supports common ancestry of cell organisms

step 1 - calvin cycle

CO2 + RuBP (sugar) = rubisco; makes 6 unstable carbon molecules that immediately split into 3 carbon molecules (3PGA)

step 2 - calvin cycle

6 ATP and 6 NADPH “bend” 3PGA twice into G3P (half a glucose molecule)

step 3 - calvin cycle

one G3P is removed and the other 5 are recycled; cycle repeats twice to make another G3P because glucose is 2 G3P

what is needed for each turn of the calvin cycle?

* 9 ATP and 6 NADPH
* 18 ATP and 12 NADPH for a whole glucose molecule

C3 plants

* most plants
* fix carbon in calvin cycle - CO2 + RuBP
* Rubisco
* most energy efficient method
* loses the most water during photorespiration

C4 plants

* tropical grasses, corn, and sugar cane
* live in dry climates
* fix carbon in cytoplasm - CO2 to PEP
* PEP - ase
* less energy efficient than C3 but more than CAM
* loses less water than C3 but more than CAM

CAM plants

* succulents, pineapple, agave
* desert plants
* only fix carbon at night, fix carbon to organic molecules
* PEP - ase
* best water conservation

how do C4 plants complete photorespiration?

PEP combines with CO2 using PEP-ase to make oxaloacetate. oxaloacetate is too big to enter bundle sheath cells so it converts to malate. malate releases CO2 to the calvin cycle. pyruvate is produced which can be turned back into PEP and reused.

how do CAM plants complete photorespiration?

during the day, CAM plants break down crassulacean acid to release CO2 to be used for the calvin cycle. process allows the stomata to stay closed in order to not loose water through transpiration.

cellular respiration

a process that is catabolic, exergonic, and requires oxygen to break down carbohydrates (glucose) to produce ATP and water

where does cellular respiration occur?

it occurs in the mitochondria of both autotrophs and heterotrophs

what is a redox reaction?

reactions that involve a transfer of electrons from one reactant to another during many chemical reactions

* reduced and oxidized

reduced

when a molecule gains an electron (becomes more negative)

oxidized

when a molecule loses an electron to another molecule

parts of cellular respiration

* glycolysis
* oxidation of pyruvate
* kreb’s cycle
* electron transport chain

anaerobic

doesn't require oxygen to occur

glycolysis

the breaking down of sugar; occurs in cytoplasm (cytosol) near mitochondria; anaerobic; all organisms do glycolysis

__10 steps in cytoplasm__

oxidation of pyruvate

occurs in matrix of mitochondria; anaerobic

__1 step in matrix of mitochondria__

aerobic

requires oxygen to occur

kreb’s cycle (citric acid cycle)

occurs in mitochondrial matrix; aerobic

__8 steps in mitochondrial matrix__

electron transport chain

occurs in cristae; aerobic

__multi - step process in mitochondrial membrane__

cristae

inner membrane of mitochondria

energy investment phase

* first 5 steps of glycolysis


* glucose (6 carbon molecule) is split into two 3-carbon molecules (G3P/GAP - glycerhaldehyde phosphate)
* 2 ATP used; 0 ATP and NADPH produced

energy yielding phase

* last 5 steps of glycolysis
* each of the two G3P molecules is converted into pyruvate
* 0 ATP used; 4 ATP and 2 NADPH produced

how much energy is harnessed during glycolysis?

about 2%

is the energy harnessed during glycolysis enough?

for small organisms like bacteria, yes, but for large organisms, no.

what occurs if oxygen is present in the cell?

cellular respiration

what occurs if oxygen is not present in the cell?

fermentation

what are the two kinds of fermentation?

* alcohol fermentation
* lactic acid fermentation

alcohol fermentation

* occurs in plants and fungi
* human use it to make beer, wine, and bread (yeast)
* end products:
* 2 ATP
* 2 CO2
* 2 ethanol’s

lactic acid fermentation

* occurs in animals
* build up causes muscle cramps and soreness
* end products:
* 2 NADPH
* 2 lactate molecules

what occurs instead of fermentation when oxygen is present?

krebs cycle

grooming phase

happens to each glucose molecule that goes through glycolysis; 2 pyruvates are produced, oxidized, and transported into the mitochondrial matrix and converted to Acetyl CoA where they then enter the Kreb’s cycle

* end products:
* 2 NADPH
* 2 CO2
* 2 acetyl CoA

what happens in the kreb’s cycle?

acetyl CoA bonds to oxaloacetic acid to make citrate. it takes two cycles to oxidize one glucose molecule. total net yield results in a pool of energy molecules that form from the oxidation of pyruvate

* end products:
* 2 ATP
* 6 NADH
* 2 FADH2
* 4 CO2

electron transport chain and oxidative phosphorylation

* occurs in cristae


* ETC and ATP synthase make ATP
* ETC pumps H+ across inner membrane and lowers H+ in the inner membrane space. this allows H+ to diffuse using the concentration gradient and ATP synthase to produce ATP.
* all NADH and FADH2 are converted to ATP
* NADH= 3 ATP
* FADH2= 2 ATP
* extra electrons are given to oxygen which combines with water
* oxygen allows electrons to move across ETC to produce ATP; without oxygen the electron wold build up and stop diffusing into mitochondria thus stopping ATP production

total net yield for prokaryotic cells during cellular respiration

* 2 ATP- glycolysis
* 6 ATP-from 2 NADH (glycolysis)


* 6 ATP converted from 2 NADH (grooming phase)
* 2 ATP -Kreb's cycle
* 18 ATP -from 6 NADH (Kreb's cycle)
* 4 ATP - converted from 2 FADH, (Kreb's cycle)

__38 Total ATP__

total net yield for eukaryotic cells during cellular respiration

• 2 ATP -glycolysis

•4 ATP -from 2 NADH (glycolysis)

•6 ATP-from 2 NADH (grooming phase)

•2 ATP- Kreb's cycle

\*18 ATP -from 6 NADH (Kreb's cycle)

•4 ATP- converted from 2 FADH (kreb’s cycle)

__36 Total ATP__