Chapter 17 Flashcards

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1
Q

What are genes?

A

Sequences of DNA that encode for proteins and how much protein should be made

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2
Q

What are mutations?

A

They occur in genes and introduce variation ; can form new alleles

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3
Q

What does Polygenic mean?

A

A characteristic that is influenced by two or more genes

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4
Q

What does epistasis mean?

A

Interactions between genes

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5
Q

Interactions between genes and the environment

A

Multifactorial

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6
Q

what does Epigenetics mean?

A

Behaviors and environment can cause changes that affect the way your genes are expressed

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7
Q

What is transcription?

A

Information from a DNA sequence is copied to a complementary RNA sequence

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8
Q

What is translation?

A

Converts the RNA sequence to an amino acid sequence

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9
Q

What does DNA polymerase do?

A

It pries the DNA strands apart and adds RNA nucleotides ; doesn’t need a primer

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10
Q

3 stages of transcription

A

Initiation, elongation, termination

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11
Q

What do transcription factors do?

A

They mediate the binding of RNA polymerase and the initiation of transcription

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12
Q

What is the transcription initiation complex made up of?

A

Transcription factors, RNA polymerase II, and a promoter

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13
Q

What does RNA polymerase do in initiation?

A

It binds to the promoter, unwinds the DNA strands and initiates RNA synthesis at the start point on the template strand

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14
Q

What does RNA polymerase do in elongation?

A

It adds nucleotides to the 3’ end of the growing strand in an anti parallel fashion

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15
Q

What does the terminator do in termination?

A

It causes the RNA pol to detach from DNA and release the transcript

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16
Q

Prokaryotic transcription

A

Transcription and translation occurs in the same physical space (no nucleus) ; mRNA that is made is directly translated into protein sequence

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17
Q

Eukaryotic processing of mRNA

A

Transcription and translation ; mRNA needs to leave nucleus to be translated ; enzymes modify pre-mRNA before the genetic messages are dispatched to cytoplasm

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18
Q

Functions of the 5’ cap

A

Protects transcript from being broken down ; helps ribosomes attach to 5’ end of mRNA

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19
Q

Functions of the poly-A tail

A

Facilitate the export of transcript from the nucleus to cytoplasm ; helps to make the transcript more stable

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20
Q

What are coding and noncoding sequences called?

A

Coding sequences are called exons and noncoding sequences are called introns

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21
Q

What happens if introns are not removed?

A

The noncoding sequences would be translated resulting in a non-functional protein

22
Q

What is alternative RNA splicing?

A

Some genes can encode more than one kind of polypeptide, depending on which segments are treated as exons during splicing

23
Q

Transfer RNA

A

tRNA enables translation of a given mRNA codon into a certain amino acid

24
Q

Codon

A

Sequential 3-letter “words” (3 bases)

25
Q

The genetic code is ____ but not ____

A

Redundant ; ambiguous

26
Q

Start codon

A

AUG ; methionine

27
Q

Stop codons

A

UAA ; UAG ; UGA

28
Q

tRNA binding sites

A

P site ; A site ; E site

29
Q

P site

A

Peptidyl-tRNA ; Holds the tRNA carry the growing polypeptide chain

30
Q

A site

A

Aminoacyl ; Holds the tRNA with the next amino acid to, be added to the chain

31
Q

E site

A

Exit ; releases the tRNAs from the ribosome

32
Q

Two instances of molecular recognition for accurate translation

A

Correct match between tRNA and an amino acid , done by the enzyme aminoacyl-tRNA synthetase ; correct match between tRNA anticodon and mRNA codon

33
Q

What is wobble?

A

Flexible pairing at the third base of a codon ; allows some tRNAs to bind to more than one codon;

34
Q

Three stages of translation

A

Initiation, elongation, termination

35
Q

Initiation of translation

A

AUG begins the formation of an initiation complex ; put together by initiation factors

36
Q

Elongation

A

Codon recognition, peptide bond formation, translocation

37
Q

Codon recognition of elongation

A

Anticodon of an incoming tRNA base pairs with the mRNA codon in site A

38
Q

Peptide bond formation in elongation

A

Catalyzed by the large ribosome subunit between amino groups of a new amino acid in site A and the Carboxyl end of the growing peptide chain in site P

39
Q

Translocation in elongation

A

Ribosome translocation the tRNA in site A to site P, at the same time the empty tRNA in P is moved to the E site where it is released

40
Q

Termination

A

When ribosome becomes filled with stop codons ; no tRNAs that complement those codons

41
Q

Nuclear localization signal (NLS)

A

Targets the protein to the nucleus

42
Q

What happens when a polypeptide has a signal directing it to the enough ER?

A

Translation will pause, and the ribosome will bind to a receptor at the RER membrane when elongation continues

43
Q

Different post-translational modifications

A

Proteolysis, glycosylation, phosphorylation

44
Q

What is proteolysis?

A

Cutting off signal sequences or cutting a long chain into final products by proteases

45
Q

What is glycosylation?

A

Addition of carbohydrates to for, glycoproteins

46
Q

Somatic mutations

A

Occur in nongermiline tissues ; can’t be inherited

47
Q

Germline mutations

A

Present in egg or sperm ; can be inherited ; cause cancer family syndrome

48
Q

Silent mutations

A

Have no effect on the amino acid produced by a codon

49
Q

Missense mutations

A

Still code for an amino acid, but not the correct amino acid

50
Q

Nonsense mutations

A

Change an amino acid codon into a stop codon ; most lead to a nonfunctional protein

51
Q

What are insertions and deletions?

A

Additions or losses of nucleotide pairs in a gene