Replication

Question 1

gene regulation

Answer 1

the process of turning genes on and off
- ensures that the appropriate genes are expressed at the proper times and helps an organism respond to its environment
- gene –(transcription)-> mRNA –(translation)-> protein

Question 2

mutations

Answer 2

permanent changes in the DNA sequences of organisms are referred to as mutations
- mutations happen during DNA replication
and are induced by environmental factors

Question 3

silent mutation

Answer 3

change in nucleotide sequence that does not change the amino acid specified by a codon
- no change; neutral

Question 4

missence mutation

Answer 4

change in nucleotide sequence that changes the amino acid specified by codon
- change in primary structure of protein; may be beneficial, neutral, or deleterious

Question 5

nonsense mutation

Answer 5

change in nucleotide sequence that results in an early stop codon
- leads to a shortened protein; almost always deleterious
- negatively impact protein function

Question 6

frameshift mutation

Answer 6

addition or deletion of a nucleotide
- reading frame is shifted, altering the meaning of all subsequent codons; almost always deleterious
- negatively impact protein function

Question 7

mutagens

Answer 7

chemicals or radiation that react with and alter DNA, such as arsenic, asbestos, and ultravlet radiation
- these changes make the molecule difficult for DNA polymerase to accurately read

Question 8

point mutation

Answer 8

mutations that alter a single nucleotide pair in the DNA

Question 9

chromatin

Answer 9

DNA and protein complex found in a eukaryotic cell
- the DNA is packaged into nucleosomes that have histone proteins as cores
- prokaryotes do not have chromatin

Question 10

chromosome

Answer 10

a single strand of chromatin or a replicated set of chromatin pieces are attached to each other at the cenromere
- chromosome is just as much DNA as it is protein

Question 11

somatic cell

Answer 11

normal body cell; anything but a gamete

Question 12

chromatids (chromatiddies)

Answer 12

one of the two identical halves of a chromosome that has been replicated in preparation for cell division

Question 13

replication

Answer 13

complementary base pairs provide a replication for DNA
- conservative, semiconservative, dispersive
- cannot be replicated heavier than before

Question 14

conservative replication

Answer 14

produces two double helices in which one helix contains entirely old parental DNA and the other helix contains entirely new DNA

Question 15

semiconservative replication

Answer 15

produces double helices in which each strand of the two double helices formed would have one old and one new strand

Question 16

dispersive replication

Answer 16

the original DNA chain breaks and recombines in a random fashion before the double helix structure unwinds and separates to act as a template for messenger RNA synthesis

Question 17

replication bubbles

Answer 17

form in chromosomes, which allow enzymes to replicate DNA
- Only happens in prokaryotes (maybe)
- most of the action go in the replication fork

Question 18

DNA polymerase

Answer 18

DNA polymerases are enzymes that catalyze the polymerization of nucleotides into DNA
- can only add a nucleotide to the 3’ end of a nucleic acid
- always building in the 5’ -> 3’ direction

Question 19

helicase

Answer 19

enzymes that break hydrogen bonds to separate the two strands of DNA

Question 20

single-strand binding proteins

Answer 20

prevent the strands from reforming a double helix

Question 21

topoisomerares

Answer 21

enzymes that alleviate the twisting as DNA strands are separated
- as helicases separate the strands of DNA, twisting tension occurs in the double helix

Question 22

primase

Answer 22

enzymes that synthesize short sections of RNA (known as primers), which allow DNA polymerases to start replication

Question 23

leading strand

Answer 23

follows the replication fork

Question 24

lagging strand

Answer 24

produced in fragments
- exonucleases remove all RNA primers, DNA polymerases replace the missing nucleotides, and DNA ligases then catalyze the last bonds

Question 25

okazaki fragment

Answer 25

short sequences of DNA nucleotides which are synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand

Question 26

DNA ligase

Answer 26

facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond
- repairs single-strand breaks

Question 27

telomere

Answer 27

regions at the ends of linear chromosomes in eukaryotes are referred to as telomeres
- an issue for lagging strands; chromosomes of most cells get shorter during each division due to this issue with replication
- DNA polymerases cannot finish replicating lagging strands due to the need for primers
- do not contain needed information but instead consist of repeating nonsense (our chromosomes end with repeats of TTAGGG)
- telomere shortening eventually causes cells to
stop dividing (usually around 40-60 divisions)

Question 28

telomerase

Answer 28

enzymes that counter the shortening of telomeres by using their own RNA templates to insert DNA nucleotides
- usually only active in germ cells (produce gametes) and some stem cells

Question 29

replication accuracy

Answer 29

DNA replication is extremely accurate due to DNA polymerases and mismatch repair
- estimate is one error per billion base pairs

Question 30

polymerase chain reaction

Answer 30

Polymerase Chain Reaction (PCR) is a lab technique that is used to replicate a specific region of DNA many times (amplification)
- DNA sample
- thermal cycler
- nucleotides
- DNA primers
- taq polymerase
- buffer solution
1. denaturing: separate strands with heat
2. annealing: anneal/attach primers to DNA
3. extension
- takes about 30 rounds of all 3