Chapter 21

Question 1

DNA is made of repeating subunits called

Answer 1

nucleotides

Question 2

A nucleotide is composed of what 3 subunits

Answer 2

One sugar (DNA- deoxyribose; RNA- ribose)
one phosphate
one nitrogenous base

Question 3

DNA nitrogenous bases

Answer 3

(A) adenine; (T) thymine; (G) guanine; (C) cytosine

Question 4

complementary base pairing

Answer 4

A-T; G-C

Question 5

Each base pair is held together by

Answer 5

weak hydrogen bonds

Question 6

The pairing of complementary bases is specific because

Answer 6

the shape of the bases and the number of hydrogen bonds that can form between them

Question 7

DNA replication begins when

Answer 7

an enzyme breaks the hydrogen bonds that hold together the paired bases that make up nucleotide strands of the double helix

Question 8

DNA polymerase

Answer 8

enzymes that link the sugars and phosphates of the newly attached nucleotides to form a new strand

Question 9

semiconservative replication

Answer 9

each daughter molecule consists of one parental strand and one new strand

Question 10

gene expression

Answer 10

DNA-> RNA-> Protein

Question 11

RNA nitrogenous bases and complementary base pairing

Answer 11

(A) adenine - (U) uracil

(G) guanine - (C) cytosine

Question 12

transcription

Answer 12

DNA -> RNA

Question 13

mRNA

Answer 13

messenger RNA carries DNA’s instructions for synthesizing a particular protein from the nucleus to the cytoplasm

Question 14

tRNA

Answer 14

transfer RNA binds to a specific amino acid and transports it to be added to a growing polypeptide chain

Question 15

rRNA

Answer 15

ribosomal RNA combines with proteins to form ribosomes

Question 16

transcription steps

Answer 16

Begins with the unwinding and unzipping of the specific region of DNA to be copied.
One of the strands of DNA serves as the template
RNA nucleotides in the nucleus pair with the complementary bases.

Question 17

promoter

Answer 17

the signal to start transcription is given by a specific sequence of bases on DNA

Question 18

RNA polymerase

Answer 18

binds with the promoter and then moves along the DNA strand opening up the DNA helix in front and then aligning the appropriate RNA nucleotides and linking them together

Question 19

introns

Answer 19

“intervening sequences” regions that do not contain codes that will be translated into protein; unexpressed regions of DNA

Question 20

The regions of mRNA corresponding to the introns are…

Answer 20

snipped out of the newly formed mRNA strand by enzymes before the strand leaves the nucleus

Question 21

exons

Answer 21

“expressed sequences” the remaining segments of DNA or mRNA spliced together to form the sequence that directs the synthesis of a protein

Question 22

translation

Answer 22

RNA -> Protein

Question 23

codons

Answer 23

sequences of 3 bases on mRNA that specify and amino acid or the beginning or end of a protein chain

Question 24

How many amino acids are there?

Answer 24

20

Question 25

Anticodon

Answer 25

Three-base sequence on tRNA that binds to the complementary base pairs of a codon on the mRNA

Question 26

Ex: a tRNA molecule with the anticodon AAG binds to what amino acid and ferries it to what mRNA codon?

Answer 26

Phenylalanine; UUC

Question 27

A ribosome consists of two subunits

Answer 27

Small and large

Question 28

Each subunit of a ribosome is composed of ____ and _______.

Answer 28

rRNA and protein

Question 29

The ribosome has two binding sites for ____ molecules and a groove for ____

Answer 29

tRNA and mRNA

Question 30

3 stages of protein synthesis

Answer 30

Initiation, elongation, and termination

Question 31

Initiation step 1

Answer 31

The small ribosomal subunit joins to mRNA at the start codon (AUG)

Question 32

Initiation step 2

Answer 32

A tRNA with complementary anticodon pairs with the start codon. Ribosomal subunits join to form a functional ribosome

Question 33

Elongation step 1 codon recognition

Answer 33

With the start codon positioned in one site the next codon is aligned in the other binding site

Question 34

Elongation step 2

Answer 34

Peptide bond formation

Question 35

Elongation step 3

Answer 35

Ribosome movement (along the mRNA)

Question 36

Termination step 1

Answer 36

Stop codon

Question 37

Termination step 2

Answer 37

Parts disassemble

Question 38

mutations

Answer 38

changes in DNA

Question 39

gene mutation

Answer 39

results from changes in the order of nucleotides in DNA

Question 40

body cell mutation

Answer 40

can affect the functioning of that cell and the subsequent cells produced by that cell

Question 41

gene mutation can be passed to offspring when

Answer 41

it is present in a gamete

Question 42

insertions

Answer 42

addition of one or more bases

Question 43

deletions

Answer 43

loss of one or more bases

Question 44

inversions

Answer 44

flipping of nucleotide positions

Question 45

duplications

Answer 45

complete copies of genes

Question 46

point mutations

Answer 46

change in one or a few nucleotides (bases)

Question 47

silent mutation

Answer 47

change does not affect the amino acid sequence

Question 48

harmless mutation

Answer 48

change amino acids in the sequence but the change does not affect protein function

Question 49

mutations can cause

Answer 49

- altered protein function (ex: sickle-cell anemia) | - destruction of protein function (ex: stop codon in wrong place)

Question 50

When regulatory proteins called ____________ _______ bind to a promoter, RNA polymerase can bind to a promoter, which begins transcription of the regulated genes

Answer 50

transcription factors

Question 51

enhancers

Answer 51

segments of DNA that increase the rate of transcription of certain genes

Question 52

_________ also specify the timing of expression and a genes response to external signals and developmental cues that affect gene expression

Answer 52

Enhancers

Question 53

DNA methylation

Answer 53

(adding a methyl group) turns off the activity of a gene by bringing in proteins that compact DNA into a tighter form