Bio 101- Exam 3 (Cellular Respiration, Fermentation, Photosynthesis, Mitosis)

Which term describes the degree to which an element attracts electrons?

Electronegativity

Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?

Anion and Cation

Which of the following statements is true of the bonds in a water molecule?

Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.

Which of the following statements is not true of most cellular redox reactions?

A hydrogen atom is transferred to the atom that loses an electron.

What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?

Ionic

Gaseous hydrogen burns in the presence of oxygen to form water:2H2 + O2 → 2H2 O + energy
Which molecule is oxidized and what kind of bond is formed?

Hydrogen, polar

Where does glycolysis occur?

cytosol

Where does the citric acid cycle occur?

mitochondrial matrix

What does the citric acid cycle produce?

transfers electrons to NADH and FADH2

What does oxygen do in cellular respiration?

Oxygen is the final electron acceptor of cellular respiration

How many NADH are produced by glycolysis?

2 NADH

In glycolysis, ATP molecules are produced by

substrate-level phosphorylation
(A phosphate group is transferred from glyceraldehyde phosphate to ADP.)

In glycolysis, what starts the process of glucose oxidation?

ATP

In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. However, the oxidation of the remaining two carbon atoms—in acetate—to CO2 requires a complex, eight-step pathway—the citric acid cycle. Consider four possible explanations for why the last two carbons in acetate are converted to CO2 in a complex cyclic pathway rather than through a simple, linear reaction.

It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.

Which of these enters the citric acid cycle?

Acetyl CoA

In the citric acid cycle, ATP molecules are produced by

subtrate-level phosphorylation

For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle.

2- Each glucose produces two pyruvates, each of which is converted into acetyl CoA.

For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle.

6- 3 NADH + H+ are produced per each acetyl CoA that enters the citric acid cycle. *2 turns*

In cellular respiration, most ATP molecules are produced by

oxidative phosphorylation

The final electron acceptor of cellular respiration is

oxygen

During electron transport, energy from _____ is used to pump hydrogen ions into the _____.

NADH and FADH2 ... intermembrane space

The energy released as electrons, which have been donated by NADH and FADH2, is passed along the electron transport chain and used to pump hydrogen ions into the intermembrane space.

What does ATP synthase do?

Phosphorylates ADP to make ATP as H+ ions pass through it

The proximate (immediate) source of energy for oxidative phosphorylation is _

kinetic energy that is released as hydrogen ions diffuse down their concentration gradient

Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops.
Which of these statements is the correct explanation for this observation?

In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration.

Suppose that a cell's demand for ATP suddenly exceeds its supply of ATP from cellular respiration.
Which statement correctly describes how this increased demand would lead to an increased rate of ATP production?

An increased demand for ATP by a cell will cause an initial decrease in the level of cellular ATP. Lower ATP decreases the inhibition of the PFK enzyme, thus increasing the rate of glycolysis, cellular respiration, and ATP production. It is the initial decrease in ATP levels that leads to an increase in ATP production.

During strenuous exercise, anaerobic conditions can result if the cardiovascular system cannot supply oxygen fast enough to meet the demands of muscle cells. Assume that a muscle cell's demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions.
What would happen to the cell's rate of glucose utilization?

ATP made during fermentation comes from glycolysis, which produces a net of only 2 ATP per glucose molecule. In contrast, aerobic cellular respiration produces about 30 ATP per glucose molecule. To meet the same ATP demand under anaerobic conditions as under aerobic conditions, a cell's rate of glycolysis and glucose utilization must increase about 15-fold.
Glucose utilization would increase a lot.

In muscle cells, fermentation produces

lactate and NAD+

In fermentation _____ is reduced and _____ is oxidized.

The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.

Match each product of pyruvate metabolism with the condition under which it is produced.

In the presence of oxygen, human cells carry out aerobic respiration, which yields acetyl CoA. In the absence of oxygen, human cells can carry out lactic acid fermentation, which yields lactate. Yeasts and many bacteria carry out alcohol fermentation, which takes place under anaerobic conditions, and produces ethanol.

Sort the following items according to whether they are reactants or products in the anaerobic reduction of pyruvate during lactic acid fermentation.
Drag each item to the appropriate bin.

When an animal engages in strenuous usage of its muscles, anaerobic conditions ensue, and pyruvate is reduced to lactate. In the process, NADH is oxidized to NAD+. This NAD+ can further oxidize glyceraldehyde-3-phosphate to produce more ATP.

The four stages of cellular respiration do not function independently. Instead, they are coupled together because one or more outputs from one stage functions as an input to another stage. The coupling works in both directions, as indicated by the arrows in the diagram below. In this activity, you will identify the compounds that couple the stages of cellular respiration.
Drag the labels onto the diagram to identify the compounds that couple each stage. Labels may be used once, more than once, or not at all.

The main coupling among the stages of cellular respiration is accomplished by NAD+ and NADH. In the first three stages, NAD+ accepts electrons from the oxidation of glucose, pyruvate, and acetyl CoA. The NADH produced in these redox reactions then gets oxidized during oxidative phosphorylation, regenerating the NAD+ needed for the earlier stages.

Redox reactions

A chemical reaction involving the transfer of one or more electrons from one reactant to another; also called oxidation-reduction reaction.

oxidation

The loss of electrons from a substance involved in a redox reaction.

Reduction

the complete or partial addition of electrons to a substance involved in a redox reaction

reducing agent

The electron donor in a redox reaction.

electron acceptor

oxidizing agent

fermentation (anaerobic respiration)

the breakdown of sugars without the use of oxygen, regenerate NAD+ so glycolysis can continue

aerobic respiration

Respiration that requires oxygen

Glycolysis

the "splitting of sugar" is a series of reactions that breaks down glucose into two pyruvate molecules, which may go on to enter the citric acid cycle, and nets 2 ATP and 2 NADH per glucose molecule

alchohol fermentation

produces alcohol and carbon dioxide from glucose when oxygen is not available

lactic acid fermentation

the chemical breakdown of carbohydrates that produces lactic acid as the main end product

beta oxidation

A metabolic sequence that breaks fatty acids down to two-carbon fragments that enter the citric acid cycle as acetyl CoA.

Chemiosmosis

A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme.

autotrophs (primary producers)

organisms that can capture energy from sunlight or chemicals and use that energy to produce food

Chloroplast

organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

Thylakoid

a membrane system found within chloroplasts that contains the components for photosynthesis

light reactions

The first of two major stages in photosynthesis (preceding the Calvin cycle). These reactions, which occur on the thylakoid membranes of the chloroplast or on membranes of certain prokaryotes, convert solar energy to the chemical energy of ATP and NADPH, releasing oxygen in the process.

Calvin Cycle

The calvin cycle in the stroma forms sugars from CO2, using ATP for energy and NADPH for reducing power

cell division

Process by which a cell divides into two new daughter cells

unicellular organism

Organisms composed of only one cell (Ex. Bacteria)

multicellular eukaryotes

plants, animals, fungi

cell cycle

series of events in which a cell grows, prepares for division, and divides to form two daughter cells

Genome

All the genetic information in an organism; all of an organism's chromosomes. It can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells)

Chromosomes

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Chromatin

complex of DNA and protein

somatic cells

(nonreproductive cells) of humans, have 46 chromosomes, 2 sets of 23

Gametes

(reproductive cells: sperm and eggs) have half as many chromosomes as somatic cells, 23 chromosomes in the case of humans

sister chromatids

Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.

Centromere

the region of the chromosome that holds the two sister chromatids together during mitosis

Mitosis

part of eukaryotic cell division during which the cell nucleus divides

Cytokinesis

division of the cytoplasm to form two separate daughter cells

Meiosis

yields nonidentical daughter cells that have only one set of chromosomes, half as many as the parent cell

Calvin Cycle

In the stroma forms sugar from CO2, using ATP for energy and NADPH for reducing power

Chlorophyll a

main photosynthetic pigment in plants

Photon

a particle of electromagnetic radiation having zero mass and carrying a quantum of energy

Photosystem

is composed of a reaction-center complex surrounded by several light-harvesting complexes

primary electron acceptor

in chloroplasts, an acceptor of electrons lost from chlorophyll a; found in the thylakoid membrane

Photosystem II

A photosystem that contains a pair of P680 chlorophyll molecules and uses absorbed light energy to split water into protons and oxygen and to produce ATP.

photosystem I

P700, makes NADPH, does not take place first

Linear electron flow

A route of electron flow during the light reactions of photosynthesis that involves both photosystems (I and II) and produces ATP, NADPH, and O2. The net electron flow is from H2O to NADP+.

C3 plants

A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.

Photorespiration

A metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; generally occurs on hot, dry, bright days, when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide.

C4 plants

plants that have adapted their photosynthetic process to more efficiently handle hot and dry conditions. They minimize the cost of photorespiration by incorporating CO2 into four-carbon compounds in mesophyll cells. These compounds are exported to bundle-sheath cells, where they release CO2 for use in the calvin cycle.

CAM plants

plants close their stomata during the day, collect CO2 at night, and store the CO2 in the form of acids until it is needed during the day for photosynthesis

miotic phase (M phase)

mitosis and cytokinesis, shortest part of cell cycle; is the interval of the cell cycle when the cell physically divides

Interphase

Includes Growth Phase 1, Synthesis Phase, and Growth Phase 2. The cell grows and DNA is replicated.

G1 phase

The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.

S phase

The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.

G2 phase

The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.

5 phases of Mitosis

prophase, prometaphase, metaphase, anaphase, telophase

Prophase

-chromosomes condense and become visible
-spindle fibers emerge from the centrosomes
-nuclear envelope breaks down
-centrosomes move toward opposite poles

Propmetaphase

-chromosomes continue to condense
-kinetochores appear at the centrosomes
-miotic spindle microtubules attach to kinetochores

Metaphase

-chromosomes are lined at the metaphase plate
-each sister chromatid is attached to a spindle fiber originating from opposite poles

Anaphase

-centromeres split in two
-sister chromatids (now called chromosomes) are pulled toward opposite poles
-certain spindle fibers begin to elongate the cell

Telophase

-chromosomes arrive at opposite poles and begin to decondense
-nuclear envelope material surrounds each set of chromosomes
-the mitotic spindle breaks down
-spindle fibers continue to push poles apart

Cytokinesis

-animal cells: a cleavage furrow separates the daughter cells
-plant cells: a cell plate, the precursor to a new cell wall, separates the daughter cells

miotic spindle

is a structure made of microtubules and associated proteins.
-It controls chromosomes movement during mitosis.

Centrosome

a type of microtubule organizing center

Centriole

is a cylindrical organelle composed mainly of a protein called tubulin. Occurs in pairs are involved in the development of spindle fibers in cell divison.

spindle microtubules

grow out from the centrosomes during their migration

aster

A radial array of short microtubules that extends from each centrosome toward the plasma membrane in an animal cell undergoing mitosis.

Kinetochores

are protein complexes that assemble on sections of DNA at centromeres

The Kinetochore microtubules

Connects the centrosome with the kinetochore in the centromere region of the chromosome.

metaphase plate

an imaginary structure at the midway point between the spindle's two poles

At which end do kinetochore microtubules shorten during anaphase?

the microtubules shorten by depolymerizing at their kinetochore ends

clevage furrow

the division in animal cell cytoplasm caused by the pinching of the cell membrane.

Cell plate

In a plant cell, midline of dividing cells during cytokinesis. Becomes the cell wall eventually.

cell cycle control system

is molecularly based; key regulatory proteins are cyclins and kinases. The cell clock has specific checkpoints where the cell cycle stops until a go ahead signal is received; important checkpoints occur in G1, G2, and M phases.

density-dependent inhibition

The phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another.

anchorage dependence

The requirement that to divide, a cell must be attached to a solid surface.