Chapter 17

Question 1

What are genes?

Answer 1

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

Question 2

What are mutations?

Answer 2

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

Question 3

What does Polygenic mean?

Answer 3

A characteristic that is influenced by two or more genes

Question 4

What does epistasis mean?

Answer 4

Interactions between genes

Question 5

Interactions between genes and the environment

Answer 5

Multifactorial

Question 6

what does Epigenetics mean?

Answer 6

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

Question 7

What is transcription?

Answer 7

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

Question 8

What is translation?

Answer 8

Converts the RNA sequence to an amino acid sequence

Question 9

What does DNA polymerase do?

Answer 9

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

Question 10

3 stages of transcription

Answer 10

Initiation, elongation, termination

Question 11

What do transcription factors do?

Answer 11

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

Question 12

What is the transcription initiation complex made up of?

Answer 12

Transcription factors, RNA polymerase II, and a promoter

Question 13

What does RNA polymerase do in initiation?

Answer 13

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

Question 14

What does RNA polymerase do in elongation?

Answer 14

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

Question 15

What does the terminator do in termination?

Answer 15

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

Question 16

Prokaryotic transcription

Answer 16

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

Question 17

Eukaryotic processing of mRNA

Answer 17

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

Question 18

Functions of the 5’ cap

Answer 18

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

Question 19

Functions of the poly-A tail

Answer 19

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

Question 20

What are coding and noncoding sequences called?

Answer 20

Coding sequences are called exons and noncoding sequences are called introns

Question 21

What happens if introns are not removed?

Answer 21

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

Question 22

What is alternative RNA splicing?

Answer 22

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

Question 23

Transfer RNA

Answer 23

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

Question 24

Codon

Answer 24

Sequential 3-letter “words” (3 bases)

Question 25

The genetic code is ____ but not ____

Answer 25

Redundant ; ambiguous

Question 26

Start codon

Answer 26

AUG ; methionine

Question 27

Stop codons

Answer 27

UAA ; UAG ; UGA

Question 28

tRNA binding sites

Answer 28

P site ; A site ; E site

Question 29

P site

Answer 29

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

Question 30

A site

Answer 30

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

Question 31

E site

Answer 31

Exit ; releases the tRNAs from the ribosome

Question 32

Two instances of molecular recognition for accurate translation

Answer 32

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

Question 33

What is wobble?

Answer 33

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

Question 34

Three stages of translation

Answer 34

Initiation, elongation, termination

Question 35

Initiation of translation

Answer 35

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

Question 36

Elongation

Answer 36

Codon recognition, peptide bond formation, translocation

Question 37

Codon recognition of elongation

Answer 37

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

Question 38

Peptide bond formation in elongation

Answer 38

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

Question 39

Translocation in elongation

Answer 39

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

Question 40

Termination

Answer 40

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

Question 41

Nuclear localization signal (NLS)

Answer 41

Targets the protein to the nucleus

Question 42

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

Answer 42

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

Question 43

Different post-translational modifications

Answer 43

Proteolysis, glycosylation, phosphorylation

Question 44

What is proteolysis?

Answer 44

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

Question 45

What is glycosylation?

Answer 45

Addition of carbohydrates to for, glycoproteins

Question 46

Somatic mutations

Answer 46

Occur in nongermiline tissues ; can’t be inherited

Question 47

Germline mutations

Answer 47

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

Question 48

Silent mutations

Answer 48

Have no effect on the amino acid produced by a codon

Question 49

Missense mutations

Answer 49

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

Question 50

Nonsense mutations

Answer 50

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

Question 51

What are insertions and deletions?

Answer 51

Additions or losses of nucleotide pairs in a gene