Chapter 16

Question 1

Genes exist as parts of chromosomes. What are the 2 chemical components of chromosomes?

Answer 1

DNA and protein

Question 2

Transformation

Answer 2

Change in genotype and phenotype (observable characteristics of an organism) due to the absorption of external DNA by cell.

Question 3

Bacteriophages aka phages

Answer 3

Viruses that infect bacteria

Question 4

Virus 🦠

Answer 4

Little more than DNA or RNA enclosed by a protective coat

Question 5

What are the 2 rules of chargaffs findings? You can use to predict % of nucleotide bases

Answer 5

1) DNA bases varies between species 2) the % of A and T bases are roughly equal and G and C are roughly equal

Question 6

Antiparallel

Answer 6

Subunit run in opposite directions

Question 7

In nitrogenous base pairing what pairs go together in the DNA double helix?

Answer 7

A with T G with C

Question 8

DNA replication

Answer 8

The copying of DNA

Question 9

What are the 3 alternative models of DNA replication?

Answer 9

Conservative model: 2 parental cells reassociate after acting as templates ***Semi conservative: 2 strands of parental molecule separate and each become part of a new pair **confirmed method** Dispersive model: each strand of birth parent and daughter molecules mix into each new template

Question 10

Origins of replication

Answer 10

Short stretches of DNA that have specific sequence of nucleotides Proteins that initiate DNA replication recognize this sequence and attach to the DNA separating the 2 strands and opening up a replication bubble

Question 11

Replication fork

Answer 11

A Y shaped region where the parental strands of DNA are being unwound

Question 12

Helicases

Answer 12

Enzymes that untwist the double helix at replication forks, separating the two parental strands and making them available as template strands

Question 13

Single strand binding proteins

Answer 13

Bind to unpaired DNA strands keeping them from re pairing

Question 14

Topoisomerase

Answer 14

Enzyme that helps relieve the strain of untwisting the helix ahead of the replication fork. Relieves strain by breaking, swiveling and rejoining DNA strands

Question 15

Primer

Answer 15

Short stretch of RNA that is an initial nucleotide chain and is synthesized by primase

Question 16

Primase

Answer 16

Synthesized an RNA primer at 5’ end of leading strand and 5’ end of each Okazaki fragments of lagging strand

Question 17

DNA polymerases

Answer 17

Catalyze the ynthesis of new DNA by adding nucleotides to the 3’ end of a pre existing chain

Question 18

DNA polymerases can only add nucleotides to what end of a primer?

Answer 18

The free 3’ end The new DNA strand can elongate only in the 5’-3’ direction

Question 19

Leading strand

Answer 19

Being made toward 5’ to 3’ direction toward the replication fork Elongates continuously

Question 20

Lagging strand

Answer 20

Made away from the replication fork Synthesized in a series of segments called Okazaki fragments

Question 21

Okazaki fragments

Answer 21

Series of lagging strand segments

Question 22

Nuclease

Answer 22

DNA cutting enzyme Cuts out damaged strands of DNA

Question 23

Nucleotide excision repair

Answer 23

DNA repair system

Question 24

DNA pol III

Answer 24

Using parental DNA as a template, synthesis new DNA strand by adding nucleotides to an RNA primer or a preexisting DNA strand

Question 25

DNA pol I

Answer 25

Removed RNA nucleotides of primer from 5’ and replaces them with DNA nucleotides added to 3’ End of adjacent fragment

Question 26

DNA ligase

Answer 26

Joins Okazaki fragments of lagging strand

Question 27

Telomeres

Answer 27

They stop the ends of DNA strands from fraying or sticking to eachother

Question 28

Chromatin

Answer 28

Complex of DNA and protein. Inside nucleus

Question 29

Euchromatin

Answer 29

Less compacted more dispersed interphase chromatin

Question 30

Heterochromatin

Answer 30

More compacted denser appearing chromatin