bio exam

prometaphase

discrete chromosomes are now visible; each consists of two aligned; identical sister chromatids. later the nuclear envelope will fragment

which statement provides the best description of the interphase portion of the cell cycle?

during interphase a cell is metabollically active

telophase

daughter nuclei are forming. cytokinesis has started; the cell plate, which will divide the cytoplasm in two, is growing toward the perimeter of the parent cell

metaphase

the spindle is complete, and the chromosomes attached to microtubules at their kinetochores are all at the plate

anaphase

the chromatids of each chromosome have separated and the daughter chromosomes are moving to the ends of the cell as their kinetochore microtubules shorten

why is it difficult to observe individual chromosomes with a light microscope during interphase?

interphase chromosomes are long, thin strands unlike the condensed chromosomes visible in mitosis

somatic cells in elephants have 56 chromosomes. how many chromosomes would be carried by the gametes produced by elephants?

28

during ______ the cell grows and replicates both its organelles and its chromosomes

interphase

during ______ both the contents of the nucleus and the cytoplasm are divided

the mitotic phase

what will be the result if a eukaryotic cell completes mitosis but does not undergo cytokinesis?

a cell with 2 nuclei each identical to the nucleus of the parent cell

a human bone marrow cell, in prophase of mitosis, contains 46 chromosomes, how many chromatids does it contain?

92

beginning with a fertilized egg (zygote) how many cells would be present in an embryo following a series of 5 cell divisions?

32

heritable variation is required for which of the following?

evolution

which of the following statements correctly describes the characteristics of recombinant chromosomes?

at least 1-3 times per chromosome pair, they carry genes from two different parents

for a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes

approx 8.4 million

what is the difference between catabolic and anabolic pathways?

catabolic pathways is the cellular process of breaking down large molecules into smaller ones, releasing energy. anabolic pathways build larger molecules from smaller ones, requires energy

what is free energy? what is its symbol?

free energy is the portion of a systems energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell. free energy is symbolized by the letter G.

in binary fission, the nuclear envelope breaks down during interphase

false

the product of a system binds to an enzyme in the same system and shuts it off. this is an example of what?

feedback inhibition

a plant whose leaves are primarily red would be the least efficient under light of what wavelength?

700 nm

which type of photosynthesis separates the light reactions and calvin cycle separately?

C4

the intermembrane space in the mitochondria has _____ than the matrix

a lower pH

moving an electron to a more electronegative molecule

releases energy

the krebs cycle turns ___ times and the calvin cycle turns ___ times per glucose molecule?

2;6

what re/places th electron donated by photosystem I to NADP+?

an electron from photosystem 2

what is an example of potential energy

a concentration gradient

a cell is performing many many dehydration reactions. this cell is performing _____ and ______ energy.

anabolism; using

what oxidizes pyruvate in pyruvate oxidation?

NAD+

what is the primary purpose of fermentation?

to regenerate NAD+ for glycolysis

when the terminal phosphate bond of ATP is broken. a molecule of inorganic phosphate P1 is formed and energy is ____ is this reaction energonic or exergonic?`

released; exergonic

what is activation energy (Ea)

activation energy is the amount of energy that reactants must absorb before a chemical reaction will start; also called free energy of activation

products

a material resulting froma chemical reaction

enzyme

a macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. most enzymes are proteins

what is a catalyst?

a chemical agent that selectively increases the rate of a reaction without being consumed by the reaction

what type of energy does water behind a dam have? a mole of glucose?

water behind a dam has potential energy. a mole of glucose also has potential energy, although more specifically, glucose has chemical energy. a term used by biologists to refer to the potential energy available for release in a chemical reaction. diffusion of ions through an ion channel is kinetic energy.

what is energy coupling? how does it drive endergonic reactions in cells? think of an example of energy coupling we discussed.

in cellular metabolism, energy coupling is the use of energy released from an exergonic reaction to drive an endergonic reaction. hydrolysis of ATP to AD{P and Pi is an exergonic reaction that is used to drive endergonic reactions or the protons diffusing across the gradient is an exergonic process used to drive the endergonic process of creating ATP

for an exergonic reaction, is G negative or positive?

an exergonic reaction proceeds with a net release of free energy. because the chemical mixture loses free energy, G is negative for an exergonic reaction

substrate

the reactant on which an enzyme works

active site

typically, a pocket or groove on the surface of the enzyme where the substrate binds and catalysis occurs

what is meant by induced fit?

induced fit is the slight change in shape of the active site of an enzyme so that it binds more snugly to the substrate

distinguish between cofactors and coenzymes give examples

a cofactor is any non protein molecule that is require for the proper functioning of an enzyme. cofactors can be permanently bound to the active site or may bind loosely and reversibly along with the substrate. during catalysis, cofactors of some enzymes are inorganic such as the metal atoms zinc, iron, and copper in ionic form. a coenzyme is an organic molecule serving as a cofactor most vitamins are important in nutrition because they. act as enzymes or raw materials from which coenzymes are made.

compare and contrast competitive inhibitors and noncompetitive inhibitiors

competitive inhibitors are substances that reduce the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics. noncompetitive inhibitors are substances that reduce the activity of an enzyme by binding to a location away from the active site. this changes the enzyme shape in such a way that the active site becomes much less effective at catalyzing the conversion of substrate to product

kinetic energy and potential energy

kinetic energy- associated with the relative motion of objects, whereas potential energy refers to an object not presently moving; it is the energy that matter possesses because of its location or structure

where do light reactions occur?

on the thylakoid membrane

what is the first law of thermodynamics? what does it mean for energy in the universe?

energy can be transferred or transformed but it cannot be created or destroyed. amount of energy in the universe is constant

2nd law of thermodynamics and what it means for energy in the universe`

every energy transfer or transformation increases the entropy ( molecular disorder) of the universe. some call this the “you always lose rule.” during every energy transfer or transformation, some energy is converted to thermal energy and released as heat becoming unavailable to do work

explain how protein structure is involved in enzyme specificity

enzymes are proteins and proteins are macromolecules with unique 3-dimensional figurations. the specificity of an enzyme results from its shape, which is a consequence of its amino acid sequence. the specificity of an enzyme is attributed to a compatible fit between the shape of its active site and the shape of the substrate

recall that enzymes are globular proteins. why can extremes of pH or very high temperatures affect enzyme activity

the 3-D structures of proteins are sensitive to their environments. as a consequence, each enzyme works better under some conditions that other conditions because these optimal conditions favor the most active shape for their enzyme molecule

describe feedback inhibition as a mechanism to control metabolic pathways?

the end product of a metabolic pathway often serves to inhibit the production of more of its own molecules. this preserves raw materials for biosynthesis

name a human enzyme that functions well in pH2. where is it found?

pepsin, a digestive enzyme is found in the human stomach

explain the difference between fermentation and aerobic respiration

fermentation is a partial degradation of sugars or other organic fuel that occurs without the use of oxygen, aerobic respiration consumes oxygen as a reactant along with the organic fuel

what are the products of glucose oxidation (cellular respiration)?

the breakdown of glucose in cellular respiration yields carbon dioxide, water and energy

both cellular respiration and photosynthesis are redox reactions. in redox reactions, pay attention to the flow of electrons. what is the difference between oxidation and reduction.

in a redox reaction, the loss of electrons from one substance is called oxidation, and the addition of electrons to another substance is known as reduction

when compounds lose electrons, they ______ energy; when compounds gain electrons they ______ energy

lose;gain

in cellular respiration, electrons are not transferred directly from glucose to oxygen. following the movement of hydrogen allows you to follow the flow of electrons. what electron carrier is hydrogen transferred to first>

NAD+

describe what happens when NAD+ is reduced. NAD+ is the _____ form, and NADH is the ____ form

the enzymatic transfer of 2 electrons and I protons ( H+) from an organic molecule in food to NAD+ to NADH ; the second protons (H+) is released. NAD+ is the oxidized (low energy) form, NADH is the reduced ( high energy form)

what is the function of the transport chain in cellular respiration?

the electron transport chain shuffles electrons down a series of redox reactions that release energy used to make a proton gradient, that is ultimately used to regenerate ATP

which strongly electronegative atom pulling electrons down the electron transport chain, is the final electron acceptor?

oxygen

explain how the electron transport is utilized in oxidative phosphorylation

this mode of ATP synthesis is powered by the redox reactions of the electrons transport chain. the energy released in each step in the electron transport chain provides the energy to maintain the chemiosmotic gradient that powers the ATP synthase complex.

the second form of phosphorylation is substance level. which stages use SLP

glycolysis and citric acid cycle

where does each stage of cellular respiration occur? glycolysis, pyruvate oxidation, citric acid cycle, oxidative phosphorylation

glycolysis= cytoplasm, pyruvate oxidation=mitochondria, citric acid cycle= mitochondria, oxidative phosphorylation= mitochondria

what is the meaning of glycolysis? what occurs in this step of cellular respiration? is oxygen required?

sugar-splitting (cutting). glycolysis is a series of reactions that ultimately splits glucose into pyruvate. glycolysis occurs in almost all living cells, serving as the starting point in fermentation or cellular respiration. NO.

the starting product of glycolysis is the six-carbon sugar _____ and the ending products are two ______ - carbon molecules of ______

glucose, three, pyruvate

glycolysis, what is the difference between the energy investment and the energy investment and energy payoff phases? what are the inputs and outputs of glycolysis?

energy investment: invest 2 ATP to phosphorylate glucose. energy payoff. oxidize G3P to create NADH+ generate 4 ATP from substrate level phosphorylation. Input is 2 ATP, glucose, 2NAD+ output is 4ATP; 2NADH, 2 pyruvate. used 2 ATP, gained 4 ATP, sum of 2 ATP gained in glycolysis

glycolysis is thought to have evolved very early in the evolution of life on earth, provide 3 pieces of evidence that justify this hypothesis

the fact that glycolysis is today the most widespread metabolic pathway among Earth’s organism suggests that it evolved very early in the history of life the cytosolic location of glycolysis also implies great antiquity. the pathway does not require any of the membrane-bound organelles that evolved approx 1 billion years after the first prokaryotic cell

explain what has happened to the six carbons found in the original glucose molecule

there are a total of le molecules of CO2 released containing the six carbons in the original glucose molecule. two molecules are released from the conversion of pyruvate to acetyl CoA and four molcules are released from the citric acid cycle

note that the little ATP has been produced by the end of CAC. where is most of the energy at this point in cellular respiration?

NADH and FADH2

explain why oxygen is considered the ultimate electron acceptor. what is its role in cellular respiration?

oxygen is extremely electronegative. it is the final electron acceptor

oxygen stabilizes the electrons by combining with two hydrogen ions to form what compound?

H2O

for aerobic respiration to continue, the cell must be supplied with oxygen the ultimate electron acceptor. what is the electron acceptor in fermentation ?

NAD+

what must be regenerated for fermentation to continue producing 2 ATP per glucose ?

NAD+

what 3 organic macromolecules are often utilized to make ATP by cellular respiration

proteins, carbohydrates and fats are utilized to make ATP by cellular respiration

for a chemotherapeutic drug to be useful for treating cancer cells, which of the following characteristics is most desirable

it targets only rapidly dividing cells

taxol is an anticancer drug extracted from the pacific yew tree that binds to microtubules and prevents their depolymerization. which phase of mitosis would be inhibited by treatment with taxol?

anaphase

cells will usually divide if they recieve the proper signal at a check-point in which phase of the cell cycle?

G1

as electrons fall from photosystem II to photosystem I, the cytochrome complex uses the energy to pump ions. this builds a proton gradient that is used in chemosmosis to produces what molecule?

hydrogen;ATP

how do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?

they have half the number of chromosomes and ¼ the amount of DNA

if the DNA content of a diploid cell in the G1 phase of the cell cycle is represented by x, then the DNA content of the same cell at metaphase of meiosis 1 would be ______

2x

which happens during meiosis I?

homologous chromosomes of a pair are separated from each other

what is the source of O2 in the atmosphere

splitting of water

where do the light reactions take place chloroplasts? the calvin cycle?

light reactions are in the thylakoid membrane; calvin cycle in the stroma

crossing over, resulting in an increase in genetic variation, occurs between ____________

nonsister chromatids of homologous chromosomes

homologous pairs of chromosomes are lined up independently of other such pairs during

metaphase I

during _____ a spindle forms in a haploid cell

prophase II

in a cell undergoing meiosis, if homologous chromosomes are aligned at the equator of the meiotic spindle, what process has occurred?

metaphase I

which event occurs in meiosis but not in mitosis?

synapsis of pairs of homologous chromosome

meiosis I produces _____ cells each of which is ______

two; haploid

crossing over, resulting in an increase in genetic variation, occurs between ____________

nonsister chromatids of homologous chromosomes

at the end of _____ and cytokinesis there are 4 haploid cells

telophase II

during ______ chromosomes align single file along the equator of a haploid cell

metaphase II

homologous chromosomes migrate to an opposite poles during ______

anaphase I

during ______ sister chromatids separate

anaphase II

synapsis occurs during

prophase I

meiosis typically produces ______ cells, each of which is _________

four; haploid

a human cell containing 22 autosomes and a Y chromosome is _______

a sperm

how does an enzyme speed up chemical reactions? (what variable does it change?)

enzymes do not change the energy that is released

write out the equation for cellular respiration (which reactants are oxidized and reduced?)

C6H12O6+6O2→6H2O+6CO2

what stages of cellular respiration is ATP made? how many in each stage?

glycolysis 2ATP, CAC 2ATP, oxidative phosphorylation 26-28-30-32 ATP

what is regenerated to keep glycolysis going? (main purpose)

NAD+

what exergonic process provides energy for ATP synthesis in oxidative phosphorylation?

chemiosmosis uses energy in H+ gradient to drive ADP+P→