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AP Bio S2 > Unit 6: gene expression and regulation > Flashcards

Unit 6: gene expression and regulation Flashcards

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1
Q

conservative model

A

the parental strands direct synthesis of an entirely new double stranded molecule
- the parental stranded are fully conserved

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2
Q

semi-conservative

A

the two parental strands: each make a copy of itself
- after one round of replication, the two daughter molecules each have one parental and one new strand

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3
Q

dispersive model

A

the material in the two parental strands is dispersed randomly between the two daughter molecules.
- After one round of replication, the daughter molecules contain a random mix of parental and new DNA

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4
Q

DNA replication begins in sites called

A

origins of replication
- various proteins attach to the origin of replication and open to the DNA to form a replication fork

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5
Q

Helicase

A

unzips DNA strands at each replication fork

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6
Q

topoisomerase

A

help prevent strain of the replication fork by relaxing supercoiling

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7
Q

Primase

A

initiates replication by adding short segments of RNA, called primers to, the parental DNA strand
Primers serve as the: foundation for DNA synthesis

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8
Q

the enzymes that synthesize DNA can only attach new DNA nucleotides to

A

to an existing strand of nucleotides

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9
Q

DNA polymerase III

A

attaches to each primer on the parental strand and moves in the 3’ and 5’ direction
- as it moves; it adds nucleotides to the new strand in the 5’ to 3’ direction

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10
Q

DNAP III follow helicase known as the

A

leading strand and requires one primer

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11
Q

DNAP III on the other parental strand moves away from the helicase is known as the

A

lagging strand and requires many primers

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12
Q

leading vs lagging strand

A

leading is synthesized in one continuous segment
-lagging strand moves away from the replication fork it is synthesized in chunks

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13
Q

okazaki fragments

A

segments of the lagging strand

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14
Q

after DNAP III form an ______, ______ replaces ____ nucleotides with ___ nucleotides

A

okazaki fragments, DNAP I, RNA, DNA

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15
Q

dna ligase

A

joins a okazaki fragment forming a continous DNA strand

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16
Q

how are genes on DNA protected from dna becoming shorter and shorter?

A

telomeres: repeating units of short nucleotides sequences that do not code for genes
- help form a cap at the end of DNA to help postpone erosion
- the enzyme telomerase adds telomeres to DNA

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17
Q

as _____ adds nucleotides to the new DNA strand, it proofreads the bases

A

-DNA polymerase

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18
Q

if segments of DNA are damaged in DNA replication…

A

nuclease can remove segments of nucleotides and DNA polymerase and ligase can replace the segments

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19
Q

protein are ____ made up of ____

A

polypeptides, amino acids (linked by peptide bonds)

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20
Q

transcription

A

the synthesis of RNA info from DNA
- allows for: “message” of the DNA to be transcribed
- occurs in the nucleus

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21
Q

translation

A

the synthesis of polypeptide using info from RNA
- occurs at the ribosome
- a nucleotide sequence becomes an amino acid sequence

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22
Q

what does mRNA do?

A

mRNA is synthesized during transcription using a DNA template
- mRNA carries info from the DNA to the ribosomes in the cytoplasm

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23
Q

what does tRNA do?

A

each tRNA carry a specific amino acid
- can attach to mRNA via their anticodon (a complementary codon to mRNA)

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24
Q

what does rRNA do?

A

-helps form ribosomes
- helps link amino acids together

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25
Q

Transcription-initiation

A
  1. RNA polymerase molecules attach to a promoter region of DNA
    - promoter regions are upstream of the desired gene to transcribe
26
Q

Eukaryote vs Prokaryote initiation transcription

A

eukaryote: promoter region is called TATA box
- transcription factors help RNA polymerase bind
Prokaryote: RNA polymerase can bind directly to promoter

27
Q

transcription-elongation

A
  • RNA polymerase opens the DNA and reads the triplet code of the template strand
  • 3’ to 5’ direction but mRNA transcript elongates 5’ to 3’
  • RNA polymerase moves downstream
28
Q

transcription- termination

A

prokaryotes:
- RNA polymerase detaches
- mRNA transcript is released and proceeds to translation
-mRNA DOES NOT need modifications
eukaryotes:
- RNA polymerase transcribes a sequence of DNA called the polyadenylation signal sequence
- codes for polyadenylation signal
- releases the pre-mRNA from the DNA
- must undergo modifications before going to translation

29
Q

5’ cap modification

A

the 5’ end of the pre-mRNA receives a modified guanine nucleotide

30
Q

poly A-tail

A

the 3’ end of the pre-mRNA receives adenine nucleotides

31
Q

both the 5’ cap and poly a tail functions

A
  • help mature mRNA leave the nucleus
  • help protect the mRNA from degradation
  • help ribosomes attach to the 5’ end of the mRNA
32
Q

RNA splicing

A

the spliceosome remove introns (do not code for AA) and joined the exons together

33
Q

prokaryote vs eukaryote ribosomes subunits

A

pro: small subunit (30s) large subunit (40s)
euk: small subunit (40s) large subunit (60s)

34
Q

what are the large subunit three sites?

A

A site: amino acid site (holds the tRNA carrying an amino acid)
P site: polypeptide site (holds the tRNA carrying the growing polypeptide chain)
E site: exit site

35
Q

Translation: initiation

A
  • small ribosomal subunit binds to the mRNA and a charged tRNA binds to start codon, AUG, on the mRNA
  • next the large subunits binds
36
Q

translation: elongation

A
  • the next tRNA comes into the A site
    -mRNA is moved through its ribosome and its codons are read
  • all organisms use the same genetic code, it supports the idea of common ancestry
37
Q

translation elongation 3 steps

A
  1. codon recognition: the appropriate anticodon of the next tRNA goes to the A site
  2. peptide bond formation: peptide bonds are formed that transfer the polypeptide to the A site tRNA
  3. translocation: the tRNA in the A site moves to the P site, then it goes to the E site. The next A site is open for the next tRNA
38
Q

translation: termination

A
  • a stop codon in the mRNA reaches the A site of the ribosome
  • the stop codon signals for a release factor
  • hydrolyzes the bond that holds the polypeptide to the p-site
  • polypeptide releases
  • all translational units dissemble
39
Q

protein structures

A

Primary: chain of amino acids
secondary: coils and folds due to hydrogen bonds forming
tertiary: side chain interaction
quaternary: 2+ polypeptide chains interacting

40
Q

some polypeptides require __ proteins to __ correctly and some require ___ before it can be ___ in the cell

A

chaperone, fold, modifications, functional

41
Q

Explain how trp operon is a repressible operon

A
  • the trp operon controls the synthesis of tryptophen
  • transcription is active
  • allosteric enzyme is only active when tryptophan binds to it
  • when too much tryptophan builds up in bacteria, it is most likely to bind to the repressor turning it active, which will then temporarily shut off transcription for tryptophan
42
Q

explain how lac operon is an inducible operon

A

the lac operon control synthesis of lactase
- transcription is off
- a lac repressor is bound to the operator (allosterically active)
- inducer=allolactose
- when present it will bind to the lac repressor and turn the lac repressor off (allosterically inactive)
- genes now can be transcribed

43
Q

How can DNA be modified?

A
  1. histone acetylation: adds acetyl groups to histones which looses the DNA
  2. DNA methylation: adds methyl groups to DNA which causes chromatin to condense
44
Q

transcription initiation

A
  • once chromatin modifications allow the DNA to be more accessible, specific transcription factors bind to control elements
  • sections of non coding DNA that serve as binding sites
  • gene expression can be increased or decreased by binding it activators or repressors to control elements
45
Q

translation initiation

A
  • translation can be activated or repressed by initiation factors
  • microRNA and small interfering RNA’s can bind to mRNA and degrade it or block translation
46
Q

morphogenesis

A

the physical process that gives an organism its shape

47
Q

mutations

A

changes in the genetic material of a cell which can alter phenotypes
- primary source of genetic variation
- any disruption can cause new phenotypes

48
Q

substitution

A

the replacement of one nucleotide and its partner with another pair of nucleotide

49
Q

silent

A

change still codes for the same AA (redundancy in the genetic code)

50
Q

missense

A

changes results in a different AA

51
Q

nonsense

A

change results in a stop codon

52
Q

frameshift mutations

A

when the reading frame of the genetic info is altered
- insertion: a nucleotide is inserted
- deletion- a nucleotide is removed

53
Q

large scale mutations

A
  1. nondisjunction: chromosomes do not separate properly during meiosis
  2. translocation: a segment of one chromosome moves to another
  3. inversion: a segment is reversed
  4. duplication: a segment is repeated
  5. deletion: a segment is lost
54
Q

transformation

A

uptaking of DNA from nearby cell

55
Q

transduction

A

viral transmission of genetic material

56
Q

conjugation

A

cell to cell transfer of DNA

57
Q

transposition

A

movement of DNA segments within and between DNA molecules

58
Q

gel electrophoresis

A
  • separate DNA fragments
  • dna is loaded into wells on one end of a gel and an electric current is applied
  • DNA fragments are negatively charged so they moved towards the + electron
59
Q

polymerase chain reaction

A
  • make several copies of a specific DNA
  • segments of DNA are amplified
  • results can be analyzed using gel electrophoresis
60
Q

dna sequencing

A

determine the order of nucleotide in DNA

AP Bio S2 (7 decks)

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