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AP Biology > Chapter 9: DNA and Its Role in Heredity > Flashcards

Chapter 9: DNA and Its Role in Heredity Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What criteria needed to be demonstrated before people could accept that DNA was the genetic material? (Circumstantial evidence)

A

present in the cell nucleus and in condensed chromosomes
doubled during S phase of cell cycle
was twice as abundant in diploid as haploid cell
showed the same patterns of transmission as the genetic info it was supposed to carry

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2
Q

Miescher

A

took bandages isolated nucleus, a solution came out that he called nuclein
said eh I bet this is genetic material

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3
Q

bacteriophage

A

viruses that infect bacteria

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4
Q

transformation experiments

A

bacteria strain A + strain B DNA —–> bacteria strain B

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5
Q

transgenic

A

artificially modified organism

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6
Q

Chargaff’s rule

A

A nd T

C and G

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7
Q

Nucleotide

A

deoxyribose in DNA, sugar in general

phosphate group

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8
Q

Purines

A

A and G

double ring

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9
Q

Pyrimidine

A

C and T

single ring

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10
Q

helical

A

spiral shape
like spring
DNA
Franklin’s Crystallography results

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11
Q

antiparallel

A

strands run in opposite directions

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12
Q

What defines DNA structure?

A

double stranded helix of unifrom diameter
right handed
antiparallel
outer edges of nitrogenous bases exposed in major and minor grooves, which exist because the helices fromed by backbones are not evenly spaced
the surfaces of A-T and G-C base pairs are chemically distinct
the binding of proteins to specific base pair sequences is the key to DNA-protein interactions

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13
Q

True or false: all regions of all DNA are right handed

A

false

Z-DNA= left handed regions

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14
Q

What functions is the double stranded helix essential to?

A

storage of genetic info (tons of nucelotides allow for lots of storage)
Precise replication during the cell division cycle (complementary base pairing)
susceptibility to mutations
expression of the coded information as phenotypes [not obvious in the structure]

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15
Q

Semiconservative replication

A

each strand of the parental DNA acts a template for a new strand, which is added by base pairing

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16
Q

What are the two general steps for DNA replication?

A

double helix unwound to separate the two template strands and get them ready for base pairing
new nucleotides form complementary base pairs with the templates and then linked by phosdiester bongs
template read in 3’ to 5’

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17
Q

Deoxyribonucleoside triphosphosphates (dNTPs) deoxyribocucleotides

A

each carry three phosphate groups
during synthesis they release the outer two in an exothermic reaction, giving the nergy for phosphodiester bond formation
between the third phosphate and the 3’ sugar position

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18
Q

DNA polymerase

A

catalyzes the addition of nucleotides as the new DNA chain grows

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19
Q

origin of replication

A

ori

pre-replication complex, with DNA polymerase, binds to it

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20
Q

replication forks

A

once the pre-replication complex is binded to the DNA, where replication happens
opens up in one direction

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21
Q

What does DNA replication begin with?

A

primer

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22
Q

primer

A

starter strand that DNA polymerase can hook on to
generally short strand of RNA
degraded at the end

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23
Q

Primase

A

enzyme that adds primer

one nucleotide at a time

24
Q

Leading strand

A

one of the newly synthesized strands

can dontinuously grow at 3’ end

25
Q

Lagging strand

A

one of the newly synthesized strands
can’t grow continuously because it orients away from the fork
short backward stretches

26
Q

Okazaki fragment

A

short stretches of new DNA on the lagging strand

27
Q

True or false: each Okazaki fragment needs a new primer

A

true

28
Q

Processive

A

DNA polymerase is this

it catalyzes many sequential polymerization reaacitons each time it binds to a DNA molecule

29
Q

DNA ligase

A

connects the okazaki fragments

30
Q

True or false: chromosomes become a little shorter with each cell division

A

true

31
Q

Telomeres

A

repetitive sequences at the end of each strand
prevents chromosomes form joining together
TTAGGG
repeats bind proteins to them
#aglets

32
Q

Telomerase

A

enzyme

catalyses the addition of lost telomeric seuences in continually dividing cells

33
Q

What happens when the chromsome ends become too short and their protective role is lost?

A

apoptosis and cell death

contains an RNA sequence that acts as a tenokate for the DNA sequence

34
Q

What are the two major repair mechanisms?

A

Proofreading- right after DNA polymerase inserts a new nucleotide when it recognizes the mistake, it removes the wrong base and tries again
Mismatch repair- after DNA has been replicated another set of proteins checks it out if there is an error, a section of the DNA will be removed and replaced

35
Q

Polymerase chain reaction

A

allows researchers to mak emultiple copies of short DNA sequences
amplification
uses a sample of double stranded DNA template
some short primers
dNTPs
DNA polymerase
salts ans buffers

36
Q

True or false: mutations are changes in the nucleotide sequence of DNA that are passed form one cell or organism to another

A

True

37
Q

Somatic Mutations

A

occur in somatic (body) cells
passed on to daughter cells
ex. patch of skin with sane mutation
NOT PASSED ON TO OFFSPRING (unless you are a plant and you follow 0 rules)

38
Q

Germline mutations

A

occur in cells of the germ line
give rise to new gametes
a gamete with mutation passes it on to new organism

39
Q

Silent mutations

A

do not affect gene function
either not expressed or have no effect
most mutations in large genomes are silent

40
Q

Loss-of-function mutations

A

rither loss of expression of a gene or in the production of a nonfunctional protein or RNA
some prevent transctiption or cause it to happen too soon
sometimes, the protein doesn’t work
generally recessive inheritance

41
Q

Gain-of-function mutation

A

protein with altered function
usually dominant
common in cancer

42
Q

Conditional Mutations

A

cause phenotypes only under certain restrictive conditions
wild-type expressed under permissive conditions
many temp sensitive

43
Q

Point mutation

A

gain, loss, or substituion of a single nucleotide

if in a gene, results in a new allele, which may result in a new phenotype

44
Q

Chromosomal Mutations

A

extensive changes in chromsome structure

change position or orientation of DNA segment without removing genetic info or cause a segment to be duplicated or lost

45
Q

Mutagens

A

environmental substances that cause mutations such as radiation or chemicals
cause point mutations

46
Q

Deletions

A

a type of chromosomal mutation
removal of part of the genetic material
ex. DNA molecules breaks at two points, the two ends rejoin and the middle is gone

47
Q

Duplications

A

a type of chromosomal mutation
ex. homologues break at different positions and then reconnect at wronf partners
one would lack a section (deletion)
another would have two (duplication)

48
Q

Inversions

A

can also result from breaking and rejoining

a segment may be removed but then flipped so it runs in the opposite direction

49
Q

Translocations

A

segments of the chromosome break off and become joined to different chromosome
may involve reciprocal exchanges
often lead to duplications and deletions

50
Q

Spontaneous Mutations

A

permanent changes in the genetic material that occur without outside influence

51
Q

what can cause spontaneous mutations to occur?

A

DNA polymerase makes a mistake (some are not caught)
Four nucleotide bases of DNA have alternate structure that affect base paring- each nucleotide can exist in two different forms(tautomers), one common one rare can pair wrongly
Bases in DNA may change because of spontaneous chemical reactions- deamination converte amino to a keto to change C to U usually repaired
Meiosis isn’t perfect- nondisjunction and aneuploidy
Gene sequences can be disrupted- random chromsome breakage/rejoining

52
Q

Induced Mutations

A

some agent from outside the cell (mutagen) causes a permanent change in the DNA sequence

53
Q

What causes induced mutations?

A 
chemicals alter nucleotide bases
some chemicals add groups
radiation damages the genetic material 
can produce highly reactive chemicals 
can break down the sugar-phosphate backbone
54
Q

True or false: mutations tend to occur in certain places

A

true

55
Q

True or falsee: mutagens can only be artificial

A

false, they can also be natural

56
Q

Benefits of mutations

A

raw material of evolution

57
Q

Costs of Mutations

A

can be harmful if result in loss of function of genes or other things that are needed for survival

AP Biology (22 decks)

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