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EXAM 2 Flashcards

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1
Q

Summarize the experiments that enabled scientists to determine that DNA made up the genetic material

A

Griffiths Experiment: attempting to develop vaccine against bacteria that causes pneumonia
-found substance necessary for bacteria to produce capsule must have passed from dea strain to living strain so transforming substances= genetic material

Hershey and Chase: found radioactive tracers for DNA but not protein
-viral DNA was responsible for directing the production of new viruses sp DNA must have genetic material

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2
Q

structure of DNA molecules

A

-chain of nucleotides made of phosphate, pentose, sugar, and nitrogen base
PURINES: double ring, adenine and guanine
PYRIMIDINES: single ring, thymine, cytosine, uracil
-sides of ladder are sugar-phosphate backbone
-rungs are complementary bases
-antiparallel: 5th carbon atom on top left, 3rd carbon atom on top right

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3
Q

why is DNA replication semiconservative

A

a new double helix has one conserved old strand and one new strand
-replication results in 2 DNA helices that are identical to each other and OG molecule

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4
Q

DNA replication process

A

1) enzyme DNA helicase unwinds the double strand DNA by breaking weak hydrogen bond between paired bases
2) new complementary DNA nucleotides fit into place by complementary base pairing
-positioned and joined thru DNA polymerase (OG template for new)
3) bc of antiparallel configuration, DNA polymerase may add nucleotide to 1 end of chain
-DNA synthesis occurs in OPPOSITE DIRECTION
-synthesis on lagging strand= okazaki fragments (short segments of DNA)
4) for completion of replication, DNA ligase connects okazaki fragments and seal break in sugar phosphate backbone
5) 2 double helix molecules are identical to each other and OG molecule

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5
Q

role of RNA in gene expression

A

transcription: 1st stage of GE, DNA serves as template for mRNA formation
translation: sequence of mRNA bases (complementary to DNA)
-determines sequence of amino acids in polypeptide
-tRNA assist mRNA during protein synthesis by bringing AA to ribosomes
-proteins determine structure/function of cells

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6
Q

mRNA

A

formed from DNA template and bearing coded info for AA sequence

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7
Q

tRNA

A

transfers amino acid to ribosome during protein synthesis
-one ends binds to AA, one end has anticodon that binds to mRNA codon

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8
Q

rRNA

A

structural form of RNA found in ribosomes

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9
Q

sequence of amino acid in a peptide, given mRNA sequence

A

transcription begins when RNA polymerase bonds to promoter (region of DNA w specialized nucleotides
-enzyme opens up for complementary base pairing
-RNA polymerase inserts RNA nucleotides to make mRNA molecule
-mRNA complementary bases= U, A, C, G

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10
Q

molecules necessary for translation

A

codon: triplet of nucleotides, DEGENERATE, most AA are coded for by MORE THAN 1 codon
stop codon: do not code AA, signal polypeptide termination
tRNA: single strand polynucleotide that doubles back on itself (boot)
anticodon: 3 base sequence in tRNA that pairs with codon in mRNA
rRNA: produced in nucleolus in eukaryotic cells and joins with proteins imported from cytoplasm to form 2 subunits
-1 binding site for mRNA, 3 for tRNA

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11
Q

Steps in Translation

A

initiation: brings components of machinery together
-protein initiation factors assemble small ribosome unit, mRNA, initiating tRNA, and large subunit for protein synthesis
(small binds to mRNA, tRNA pairs with mRNA, large completes it)

elongation: polypeptide increases in length one AA at a time
1) tRNA with attached P site, other tRNA carrying AA to amino site
2) once the tRNA is at the A site, the peptide chain is transferred from P site tRNA to A site tRNA
3) energy and part of ribosomes bring about transfer, energy makes peptide bond longer
4) translation occurs, mRNA moves forward 1 codon length and peptide tRNA shifts to P site, tRNA with no peptide exits
-new tRNA enters A site

termination: final step, components separated
1) ribosome comes to a stop codon on mRNA and release factor binds to the site
2) release factor hydrolyzes the bond between the last tRNA at P site and polypeptide (THE ARE RELEASED AND SEPARATED), ribosome subunits disassociate

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12
Q

causes of gene mutations

A

errors in DNA replication
-DNA polymerase proof reads the new strand against old strand
mutagens
-radiation (UV or X ray) inorganic chemicals (pesticides, ciggy smoke)
transposons: specific DNA sequence can move within and between chromosomes

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13
Q

describe the effect that gene mutations have on cells

A

point mutations: chaning in single DNA nucleotide, alters transcription and amino acid
-base substitution: 1 DNA nucleotide being replaced with incorrect nucleotide
frameshift mutation: 1 or more nucleotides are inserted or deleted from DNA (new sequence of codons)
nonfunctional proteins: ruin metabolic pathway

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14
Q

why cancer is a failure of genetic control

A

cancer cells are genetically unstable (tumor undergoes many mutations)
-do not correct regular cell cycle, it just increases in cell division
-it escapes signals from death/apoptosis and continues to divide despite damage
-can survive and proliferate elsewhere
(metastasis: spread of cancer from place of origin to body, invading tissues
angiogenesis form of new blood cells (rapid=cancer))

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15
Q

benign

A

noncancerous mass of cells from single mutated cell that has repeatedly undergone cell division

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16
Q

malignant

A

cancer cells
ability to move and threat life

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17
Q

telemores

A

tip of end of chromosome that shortens with cell division and may regulate the number of times a cell can divide

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18
Q

metastasis

A

spread of cancer from place of origin to body (caused by migration)

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19
Q

angigenesis

A

form of new blood cells (rapid = cancer)

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20
Q

stages of cell cycle

A

interphase: growth and DNA synthesis occur when cell is NOT dividing
G1: main checkpoint, if DNA is damaged apoptosis will occur otherwise cells will commit to dividing
G0: nerve and muscle cells that pause (no longer prep division and enter this phase if cells are damaged) if no repair, then they die
S: DNA REPLICATION, 1 chromatid turns into 2 sister chromatids with identical DNA sequences
G2: cell synthesizes proteins needed for division in microtubules
mitotic stage: mitosis (division of nucleus and genetic material) daughter chromosones
cytokinesis: (division of cytoplasm) 2 daughter cells

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21
Q

apoptosis

A

enzymes bring about death, cell round up and loses contact with neighbors
chromatin condenses and nucleus fragments
plasma membrane blisters and blebs form
cell fragments engulfed by white blood cells

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22
Q

distinguish the external and internal controls of the cell cylce

A

internal: control timing events
external: growth factors, tell cell to divide

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23
Q

cell cycle checkpoints

A

G1 = allows cell to determine whether conditions are favorbale to being cell cycle
G2 = stop sif DNA hasn’t finsihed replicating
M = cycle stops if chromosones are not distrib. accurately to daughter cells

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24
Q

difference between proto-oncogenes and tumor suppressor genes

A

proto-oncogene: encode proteins that promote cell cycle and prevent apoptosis (gas pedal)
-oncogenes: cancer causing gene (a mutation)
tumor suppressor: encodes protiens that slow cell cycle down (breaks)
-when mutated, products DO NOT inhibit cell cycle
ex: P53 (all cancer) BRCAI (breast and ovarian cancer)

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25
Q

role of mitosis in a cell and chromosome number

A

chromatin = DNA and protein
-humans have 46 chromosomes and 23 pairs
diploid: 2 of each type of chromosome present
haploid: cells with half (1 of each type of chromosome) 23 CHROM.

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26
Q

what is mitosis?

A

sister chromatids separate into daughter chromosomes then are distributed to 2 daughter nuclei

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27
Q

prophase

A

centrosomes move away to opposite ends of nucleus
-miotic spindle fibers begin forming
-spindle fibers are made of tubulin
-DNA condensed into chromosomes
-ORGANIZED BY CENTROSOMES

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28
Q

prometaphase

A

nuclear envelop breaks down
-kinetochores hook up to spindle fibers
-kinetochores have motor proteins that pull chromosomes along fibers

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29
Q

metaphase

A

chromosomes align in center of meta plate
-each chromosome has 2 kinetochores (one for each chromatid)
-spindle microtubules are on OPPOSITE POLES

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30
Q

anaphase

A

centromeres of sister chromatids separate
-kentechore drags daughter chromosomes to opposite poles
(spindles shorten)

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31
Q

telaphase

A

OPPOSITE OF PROPHASE
-spindle reduce in size, nuclear envelop reforms
-chromosomes uncoil and lengthen

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32
Q

cytokinesis

A

cytoplasm the chromosomes into 2 separate cells

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33
Q

mitosis in animals vs plants

A

A: centrosomes contain centrioles
P: no centrioles
meristematic tissue has ability to divide
just has centrosome and spindle fibers

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34
Q

cytokinesis in animals vs plants

A

A: in telophase, cleavage furrow (indent of membrane between 2 nuclei) forms
-forms contractile ring to construct daughter cells
-separates cytoplasm

P: cell wall prevent furrowing
-builds new cell wall between cells (small flat disk)
-golgi produces vesicles for cell plate
-membrane of vesicles finishes membrane of cells complete= release molecules to form new cell walls

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35
Q

meiosis

A

occurs in sexually reproducing organisms
-reduces number of chromosomes in half
-genetic variation from both parents
-begins with 1diploid parent and ends with 4 haploid daughter cells

36
Q

homologous pairs

A

ARE ALIKE NOT IDENTICAL
match in length, centromere position, and gene location
-different version of gene found in same locus (1 allel from mom, 1 from dad)

37
Q

meiosis 1

A

turn to haploid!!
prophase: homo. chromosomes come together @ synapsis
-each pair with 4 chromatids = tetrad
-NON SISTER CHROMATIDS CROSS OVER
metaphase: align at meta plate
-independent assortment: randomly assemble
Anaphase: HC separate and pulled top opposite poles of spindle fibers
telophase: daughter cells have 1 chromosome ( next cell divide)

38
Q

meiosis 2

A

4 daughter cells are produces wuth haploid chromosomes
daughter cells are called gametes (egg and sperm fuse)
fertilization restores diploid #

P: cells have 1 chromosome from each HC pair
M: chromosomes align at meta plate
A: sis chromatids separate becoming daughter chromosomes and move to opposite poles
T: spindle disappear, nucleus forms, cytokinesis

39
Q

compare and contrast mitosis and meiosis

A

DNA replication takes place prior to both BUT meiosis is 2 nucelar divisions and mitosis is 1
-meiosis= 4 daughter cells while mitosis = 2 daughter cells
-meiosis is haploid (not identical), mitosis is diploid (identical)

40
Q

human life cycle

A

zygote: diploid cell formed by union of 2 gametes (production of fertilization)
mitosis is involved in the growht of a child and repairs tissues

41
Q

spermatogenesis

A

in testes and begins at puberty
-primary spermatocytes divide in meiosis then divide again in meiosis 2 to produce 4 spermatids (spermatids mature to sperm)

42
Q

oogenesis

A

in fetus, primary oocytes are arrested at P1
resumes at puberty and primary oocyte contains meiosis each menstrual cycle
-primary oocyte divides in Meiosis 1, if secondary is fertilized meiosis 2 will proceed
-if not it disintegrates

43
Q

equation for cellualr respiration

A

C6H12O6 + 6O2 => 6CO2 + 6H2O
produces 36-38 ATP molecules

44
Q

role of electron carriers in CR

A

NAD+: coenzyme in oxidation reductions that accepts electrons and hydro ions to become NADH (carries to ETC)
NAD+ cycle: coenye NAD+ accepts hydrogen atoms and NADH results, when NADH passes on electrons, NAD+ results
FAD: coenzyme in oxidation reduction that becomes FADH2 (carries electrons to ETC)

45
Q

what are the aerobic and anaerobic faces of CR

A

glycolysis: outside mitochondria and does not use oxygen
citric acid cycle and prep reaction: in matrix, use oxygen, give of CO2
ETC: in cristae, use oxygen

46
Q

glycolysis

A

takes place within in the cytoplasm and results in the break of glucose into 2 pyruvate molecules
INPUTS: 6 carbon glucose, 2 NAD+, 2ATP, 4ADP, 2 phosphate
OUTPUT: 2 (3 CARBON pyruvate), 2NADH, 2ADP, 4 ATP (2 ATP net gain)

47
Q

energy investment

A

2 ATP are used to activate glucose (6C)
-results in splitting into 2 (3C) pyruvate with attached phosphate group

48
Q

energy harvesting steps

A
  1. oxidation of pyruvate occurs by removal of hydrogen atoms
    -hydro atoms are picked up by NAD+ and NADh results (NADH will later pass thru ETC )
    -4 high energy phosphate groups results
  2. substrate level ATP synthesis: ATP is formed by transferring phosphate from metabolic substrate to ADP w enzyme
  3. oxidation occurs by removal of water
  4. substrate level synthesis results in 2 molecules of pyruvate with 2 more ATP made
49
Q

how can ATP be produced with no oxygen

A

is o2 is limited, pyruvate molecules accumulate in the cell and intermediates (Nad, Fad) cannot be recycled
fermentation: anaerobic breakdon of glucose that results ina gain of 2 ATP and end products

50
Q

advantages and disadvantage of fermentation

A

lactic acid and alcohol: helps recycle NAD+ molecules and allows glycolysis to proceed ATP production
-fermentation yields only 2 ATP molecules
-toxic to cells
-release CO2

51
Q

preparatory reaction

A

pyruvate is converted to 2 carbon acetyl group attached to CoA where CO2 is given off
-oxidation reaction where hydro atos are removed from pyruvate by NAD+ resulting in NADH (occurs twice)
OUTPUT: 2 NADH, 2CO2, 2acetyl coA

52
Q

citric acid cycle

A

TURNS TWICE, MULTIPLY BY 2
-C2 acetyl group w Co A joins with C4 molecules creating a C6 citrate
-oxidation produces 2NADH
-loss of CO2 = C4 molecule
-1ATP produced by substrate level synthesis
-additional oxidation = FADH2, NADH, regeneration of OG C4 molecule
INPUTS: 2 acetly groups, 6 NAD, 2 FAD, 2ADP + 2P
OUTPUT: 4CO2, 6NADH, 2FADH, 2 ATP

53
Q

electron transport chain

A

series of protein carries that pass electrons form 1 to another
-electron carriers are called cytochromes (iron molecules)
-NADH and FADH2 arrive carrying high energy electrons (two per carrier)
-as electrons are passed from each protein, electron gradient is generated
-once gradient reaches a certain level, ATP synthase enzyme uses energy in gradient to re-energize ADP forming ATP
-oxygen is used as terminal electron acceptor

54
Q

compare and contrast autotrophs and heterotrophs

A

autotrophs: photosynthesis carbohydrates, make their own food (plants)
heterotrophs: CANNOT synthesize its own food, consumes organic material made by autotrophs
Both of them use organic molecules produced by photosynthesis for growth and repair and a source of chemical energy for work

55
Q

role of photosynthesis for all organisms on earth

A

humans and all organsisms release CO2 in the air as a waste product from metabolic pathways such as cellular respiration. Some of the same CO2 is entered into the leaf through the stomata and is converted into carbohydrates
Glucose is the main form of energy

56
Q

overall chemical equation for photosynthesis

A

6CO2+6H2O ==> C6H12O6 + 6O2

57
Q

two sets of reactions in photosynthesis

A

light reactions: captures solar energy, takes place in thylakoid membrane, releases oxygen and provides molecules for Calvin
NADP+ carries hydrogen atoms from light to Calvin, when accepted, becomes NADPH
Calvin Cycle: in stroma of chloroplasts, uses the products of light reaction to reduce CO2 to a carb
ATP CARRIES ENERGY FROM LIGHT TO CALVIN

58
Q

structure of chloroplasts

A

tbd

59
Q

pigemmnets required to absorb light

A

chlorophylls a and b absorbs violet, indigo, blue, and red light, green light is reflected so we see green
carotenoids absorb violet-blue-green range reflecting yellow or orange colors
photosynthesis begins when these pigemnts absorb light

60
Q

noncyclic electron pathway

A

electron flow traced from water to NADP+
-2 photosystems which are a pigement complex and electron acceptors within thylakoid membrane
-is like an antenna for gathering solar energy

61
Q

photosynthesis in thylakoid membrane

A

Photosystem 2: pigment complex and electron acceptors, water is split to replace energized electrons and O2 is released, ATP is made

ETC: carries electrons from PSII to PS I, uses energy to pump hydro ions from stroma to thylakoid space

Photosystem 1: pigemtn complex and electron acceptors, adjacent to enzyme that reduces NADP+ to NADPH

ATP synthase complex: has channel for hydro ion flow, and flow drives ATP synthase to join ADP and P

62
Q

Identify the electron donor and electron acceptors in the light reactions

A

water is an electron donor
electron acceptor is NADP+ which turns to NADPH

63
Q

Describe why the H+, proton, gradient across the thylakoid membrane is referred to as a storage of energy.

A

Thylakoid space acts as a reservoir for hydrogen ions (H+)
-H+ from water being split within thylakoid space
-pumped in by electron transport chain
-More H+ in thylakoid space than stroma
Electrochemical gradient
H+ can only flow through ATP synthase
Energy powers making ATP by chemiosmosis

64
Q

Fixation of Calvin Cycle

A

step 1!!

3 molecules of CO2 are attached to 3 RuBP
-results in 3 6-carbon molecules
-then splits in half forming 6 3-carbon molecules (1st 3C molecule is 3PG)
-attachment of CO2 and RuBP is catalyzed by RuBP carboxylase

65
Q

Reduction of Calvin Cylce

A

step 2!!

-using ATP, 3PG changes to BPG
-this causes ATP to turn to ADP+P
-using NADPH, BPG then becomes G3P
-this causes NADPH to become NADP+

66
Q

Regeneration of RuBP in Calvin Cycle

A

step 3!! TAKES 3 TURNS OF CYCLE

-5 molecules of G3P become 3 molecules of RuBP
-3 molecules of ATP become 3 molecules of ADP + P
-remaining G3P is used to make glucose

67
Q

uses of G3P

A

-can be combined with fructose to form sucrose for transportation of carbs
-starting point of synthesis of starch and cellulose (starch is storage of glucose found in chloroplasts and amyloplasts of roots) (cellulose is the structural component of the plant cell and becomes fiber in our diet)
-can form fatty acids and glycerol to combine to make plant oils (sunflower, olive oil, corn oil, etc)

68
Q

Compare the overall chemical equations for photosynthesis and cellular respiration.

A

photosynthesis products are the reactants for cellular respiration

69
Q

Describe the similarities and differences between cellular respiration and photosynthesis

A

z

70
Q

In a chloroplast, where is carbon dioxide used to produce a carbohydrate

A

stroma
stomata are small lip openings for CO2

71
Q

what is chemiosmosis

A

The H+ ions flow through an ATP synthase complex, back into the matrix.
As the H+ pass through the complex, energy is released and captured to form ATP from ADP
(through ATP synthase complex to make ATP, through channel protein to release it)

72
Q

mesophyll

A

tissue in leaves specialized for photosynthesis

73
Q

where do products of photosynthesis come from?

A

glucose comes from CO2, oxygen comes from H2O

74
Q

The individual(s) credited with the discovery of the structure of DNA is (are)

A

watson and crick

75
Q

Which does NOT describe a function of the DNA polymerase molecule?

A

synthesize the proper nucleotide to match with the base read on the old strand

76
Q

Which of the classes of RNA molecules carries the genetic information from the nucleus as it is needed for the construction of a protein

A

MRNA

77
Q

The ______ contain(s) the information for the structure of the protein.

A

exons!!
introns intervene

78
Q

Upon examination, a cell is found to have twice as much DNA as the normal diploid state but is no longer in the process of replicating the DNA. All of the DNA is found within a single nucleus. Which stage of the cell cycle is this cell in?

A

g2

79
Q

Which of the following is NOT true concerning the checkpoints in the cell cycle?

A

The p53protein causes the cell to divide even if the DNA is damaged.

80
Q

What lines up at the metaphase plate during metaphase II of meiosis and metaphase of mitosis

A

each chromosome composed of two sister chromatids at both

81
Q

What lines up at the metaphase plate during both metaphase I of meiosis and metaphase of mitosis

A

homologous chromosomes for meiosis, each chromosome is composed of two sister chromatids for mitosis

82
Q

Which of the following statements is NOT true about oogenesis in humans?

A

Four equal size daughter cells will form.

83
Q

Why do organisms without oxygen need to convert pyruvate to lactate?

A

in order to regenerate NAD+

84
Q

ATP and ADP have a strong negative charge. How could that get into and out of the mitochondrion

A

Through a membrane transport protein.

85
Q

what is the innermost membrane of the chloroplast

A

thylakoid membrane

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