Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology 151 (Semester 1) > Chapter 17 > Flashcards

Chapter 17 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

gene expression

A

the process by which DNA directs the synthesis of proteins (or in some cases, just RNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

one gene-one enzyme hypothesis

A

says that a gene dictates which specific enzyme is produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

transcription

A

o Synthesis of RNA using info from DNA
o DNA–>RNA
o Information is simply ‘re-written’ from DNA to RNA
o DNA can serve as complementary sequence to producing RNA
o Synthesis of any kind of RNA from a DNA template

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

ribosomes

A

sites for translation

• Facilitate the linking of amino acids into polypeptide chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

primary transcript

A

o The initial RNA transcript from any gene that is not translated into protein
o Initial RNA transcript–> pre-mRNA –> mRNA
o Includes the genes specifying RNA
o

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Triplet code

A

the genetic instructions for a polypeptide
o triplet code–> mRNA–> amino acids
o Is then transcribed into 3-nucleotide (non overlapping) words in mRNA
o Responsible for the flow of info from gene –> protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

template strand

A

the strand being transcribed

o provides the template for the sequence of nucleotides in an RNA transcript

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

codon

A

mRNA nucleotide triplets
o There are 64
o Written in 5’→3’ direction
o This term is also used for DNA nucleotide triplets along the nontemplate strand
o Each codon specifies which amino acid will be placed in certain position along a polypeptide
o There are 3x the amount amino acids as there is protein product

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Initiation (Transcription)

A

After RNA polymerase binds to promoter, DNA strands unwind and polymerase initiates RNA synthesis at starting point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Elongation (Transcription)

A

The polymerase moves downstream, unwinding DNA and elongating RNA 5’-→3’. Then, DNA strands reform a double helix
• Nucleotides are added to the 3’ end of growing RNA molecule
• Occurs at 40 nucleotides/sec.
• **A single gene can be transcribed by several molecules of RNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Termination (Transcription)

A

RNA transcript is released and polymerase detaches from DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

RNA polymerase

A

separates the 2 strands of DNA and joins RNA nucleotides complementary to DNA template strand
• Essentially elongates RNA polynucleotide
• Works only 5’→3’
• Doesn’t require a primer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

promoter

A

area where RNA polymerase attaches and begins transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

terminator

A

the sequence that signals the end of transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

RNA polymerase II

A

used for pre-mRNA synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

transcription unit

A

stretch of DNA ‘downstream’ from the promoter (direction of transcription) that is transcribed into RNA molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

start point

A

nucleotide where synthesis begins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

transcription factors

A

collection of proteins in eukaryotes that mediate the binding of RNA polymerase and the initiation of transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

transcription initiation complex

A

the complex of transcription factors and RNA polymerase II bound to the promoter
• 1) Eukaryotic promoter contains the TATA box. A nucleotide sequence containing ‘TATA’
• 2) Several transcription factors (including one recognizing the TATA box) must bind to the DNA before the RNA polymerase II can bind in correct location and orientation.
• 3) DNA, RNA, polymerase II, and other transcription factors bind to form the transcription initiation complex.
 RNA polymerase II then unwinds DNA double helix, and RNA synthesis begins at start point on template strand.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

TATA box

A

crucial promoter DNA sequence
• Found in eukaryotic promoter
• Nucleotide sequence containing ‘TATA’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

upstream/downstream

A

upstream-5’ end

downstream-3’ end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

RNA processing

A

enzymes in the nucleus modify pre-mRNA in ways that the message is sent to the cytoplasm
• This produces mRNA ready for translation!
• When mRNA reaches the cytoplasm and attaches to it with its modified ends, ribosome attachment is facilitated!
• Remember, 5’-cap and poly-A tail are not translated into protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

5’ cap

A

A modified form of guanine nucleotide added onto 5’ end of an pre-RNA molecule after transcription of first 20-40 nucleotides
• Part of the pre-mRNA molecule which is synthesized first
o Then the 3’ end of pre-mRNA is modified before mRNA exits nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

poly-A tail

A

when an enzyme adds 50-250 adenine nucleotides to the 3’ end of an pre-RNA molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

UTR

A

parts of the mRNA that are not translated into protein, but have other functions such as ribosome building

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

RNA splicing

A

removal of large portions of RNA molecule that is initially synthesized
• Introns cut out, exons ‘spliced’ together
• Occurs in nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Spliceosome

A

complex of proteins and small RNA’s which carry out the removal of introns
 Binds to short nucleotide sequences along an intron
 Intron is then released, exons join

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Introns

A

‘intervening’ or noncoding sequences of nucleic acid that lie between coding regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Exons

A

coding regions of nucleic acid that are eventually expressed by being translated into amino acid sequences
• ‘Exit’ the nucleus
• Exceptions: UTR’s of the exons of RNA

30
Q

Ribozymes

A

RNA molecules that function as enzymes
• Pre-rRNA removes its own introns
• The discovery of ribozymes falsified the idea that all biological catalysts are proteins.

31
Q

Alternative RNA splicing

A

genes which give rise to 2 or more different polypeptides

• As a result, the number of different protein products an organism produces can be GREATER than its no. of its genes

32
Q

Domains

A

structural and functional regions found in the architecture of proteins

33
Q

exon shuffling

A
  • Introns allow crossing-over

* Results in new combinations of exons and proteins

34
Q

translation

A

As tRNA moves in ribosome, codon is translated into amino acid. Each tRNA has anticodon on one end and corresp. a. a. on the other.
o Amino acid is added to polypeptide chain when anticodon H bonds to complementary codon on mRNA.
o mRNA –> nucleotide sequence –> amino acid –> polypeptide
o Occurs in ribosome

35
Q

tRNA

A

‘translator’
o Functions to transfer amino acids from cytoplasm to growing polypeptide in ribosome
o Each tRNA molecule is associated with one specific amino acid
o Made in nucleus

36
Q

anticodon

A

nucleotide triplet that base-pairs to a specific mRNA codon

o Usually written 5’→3’

37
Q

Aminoacyl-tRNA synthetases

A

enzymes that carry out correct matching tRNA to amino acid
o 20 exist for each amino acid
o After tRNA is attached to amino acid, aminoacyl-tRNA is released and can deliver its amino acid to growing polypeptide chain

38
Q

wobble

A

the relaxed base paring at the 3rd base of a codon attached to the corresponding tRNA anticodon
o Why some tRNA’s are able to bind to more than one codon. This is because

39
Q

rRNA (ribosomal RNA)

A

proteins that make up the small and large subunits of a ribosome
• Eukaryotes- subunits are made in the nucleus. RNA is then assembled with proteins from cytoplasm.
 Have slightly LARGER ribosomes than bacteria!
• Main constituent of ribosomes?

40
Q

P site (peptidyl-tRNA binding site):

A

holds the tRNA carrying the growing polypeptide chain

41
Q

A site (aminoacyl-tRNA binding site):

A

holds tRNA carrying the next amino acid to be added to the chain

42
Q

E site (exit site):

A

where discharged tRNA’s leave the ribosome

43
Q

Initiation (Translation)

A

o Brings together mRNA, tRNA, and 2 subunits of a ribosome
o Small ribosomal subunit binds mRNA and specific intiator tRNA (containing methionine)
• Eukaryotes- small subunit binds to the 5-cap of mRNA and moves downstream until mRNA reaches the start
 Initiator tRNA then H bonds to Met (AUG)
 This step determines the codon reading frame
• Bacteria- mRNA is binded at a specific mRNA sequence
o After translation initiation complex is complete, the initiator tRNA sits on P site and vacant A site is ready for next aminoacyl tRNA
• Energy provided by GTP

44
Q

Elongation (Translation)

A

o Amino acids are added to C-terminus of chain
o 1) Codon Recognition
o 2) Peptide bond formation
o 3) Translocation

45
Q

Codon Recognition (Elongation)

A

Anticodon of incoming aminoacyl-tRNA base-pairs with complementary mRNA codon in A site
• Hydrolysis of GTP powers this step

46
Q

Peptide Bond formation (Elongation)

A

The polypeptide from the tRNA in the P site is removed and attached to the tRNA in the A site
• rRNA molecule of a large ribosomal subunit catalyzes formation of peptide bond here

47
Q

Translocation (Elongation)

A

Ribosome tRNA in A site moves to P site. Empty tRNA in P site moves to E site. Next codon is brought to be translated in the A site.

48
Q

Translation initiation complex

A

union of mRNA, initiator tRNA, and large and small ribosomal subunit

49
Q

initiation factors (translation)

A

proteins required to bring units of the translation initiation complex together

50
Q

Elongation factors

A

proteins which help with the addition of amino acids

51
Q

Termination (Translation)

A

o Elongation continues until ribosome reaches a stop codon on the mRNA. Then, the A site of the ribosome accepts a ‘release factor’ (protein shaped like tRNA).
o Release factor hydrolyzes (breaks) the bond between completed polypeptide and tRNA in P site. Polypeptide is free.
o Two ribosomal subunits, etc. dissociate. Polypeptide then exits through large subunit.
o This process requires 2 GTP molecules

52
Q

release factor

A

protein shaped like aminoacyl tRNA
• Adds water instead of amino acid to chain
• Promotes termination of translation

53
Q

chaperonin

A

a protein that can help a polypeptide fold correctly

54
Q

post-translational modifications

A

additional steps required before the protein can do its job in the cell
• For example, amino acids may need to modified by attaching sugars, lipids, removing polypeptides etc.

55
Q

free ribosomes

A

synthesize proteins that stay and function in cytosol

56
Q

bound ribosomes

A

make proteins of endomembrane system and proteins secreted by the cell
• Attached to cytosolic side of ER or to nuclear envelope

57
Q

signal polypeptides

A

marks polypeptides of proteins destined for endomembrane system or for secretion

58
Q

Signal-recognition particle (SRP)

A

protein-RNA complex which functions as an escort to bring the ribosome to the receptor protein built in the ER membrane. Polypeptide synthesis continues there
• targets a protein to the ER
• 1) Polypeptide synthesis begins on a free ribosome.
• 2) SRP binds to signal peptide, stopping synthesis.
• 3) SRP binds to receptor in ER membrane (that has a signaling molecule).
• 4) SRP leaves and polypeptide synthesis continues with translocation across the membrane.
• 5) Signal-cutting enzyme cuts of signal peptide.
• 6) Rest of completed polypeptide leaves ribosome and folds into final conformation.

59
Q

Polyribosomes/polysomes

A

strings of ribosomes that can translate more than one mRNA at a time
• As a result, one mRNA can produce many polypeptides

60
Q

large-scale mutations

A

chromosomal arrangements that affect long segments of DNA

61
Q

small-scale mutations

A

changes in nucleotide pairs

62
Q

point mutations

A

changes in a single nucleotide pair of a gene
o If this occurs in gamete, it will be transmitted to offspring
o Responsible for sickle cell anemia

63
Q

nonsense mutations

A

point mutation which changes a codon for an amino acid into a stop codon
• Stops translation

64
Q

nucleotide-pair substitution

A

replacement of a nucleotide and its partner with another pair of nucleotides

65
Q

silent mutations

A

substitution mutation when a change in codon is transformed into a new codon that codes for the same amino acid

66
Q

missense mutations

A

substitution mutation when codon is changed into a new codon that codes for a new amino acid
• Can have little effect on protein
• Accounts for most substitution mutations

67
Q

insertions and deletions

A

additions or losses of nucleotide pairs in a gene
• Potentially disastrous for protein
• Usually results in premature termination or nonsense/nonfunctional

68
Q

frameshift mutation

A

an insertion/deletion that shifts the reading frame

69
Q

spontaneous mutations

A

the mutation that results when a nucleotide is matched with an incorrect base which will be used as a template strand in the next round of replication

70
Q

mutagens

A

physical and chemical agents that interact with DNA to cause mutations
• Ex: carcinogens

71
Q

elongation factors (Translation)

A

proteins which help with the addition of amino acids

72
Q

mRNA

A

mRNA: carries genetic info from DNA to protein-synthesizing machinery of the cell

Biology 151 (Semester 1) (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions