UNIT 2 - DNA replication

Question 1

who discovered DNA

Answer 1

James Watson and Francis Crick

Question 2

what is Chargaff’s rule

Answer 2

states that DNA from any cell should have a 1:1 ratio of purine bases and pyrimidine

Question 3

how do the strands run in DNA?

Answer 3

antiparallel 5’-3’

Question 4

what are the “rungs” of the ladder paired with in DNA?

Answer 4

nitrogen bases

Question 5

how many base pair rungs make one full twist of the helix in DNA?

Answer 5

10 base pair rungs

Question 6

what is a gene?

Answer 6

a specific section of chromosomes that codes for a protein

Question 7

what is the process where DNA makes identical copies of itself called?

Answer 7

semi-conservative

Question 8

what must happen within DNA before a cell can divide?

Answer 8

DNA must replicate before

Question 9

what is interphase?

Answer 9

when cells prepare for division through growth and duplication of cell contents

Question 10

what is mitosis?

Answer 10

nuclear division: duplicated chromosomes are separated and move to opposite poles of the cell

Question 11

what is cytokinesis?

Answer 11

cell division: cell contents divide and two new daughter cells are produced

Question 12

what is step 1 of DNA replication?

Answer 12

unzipping:
- DNA double helix unwinds
- Helicase enzyme breaks hydrogen bonds holding the nitrogenous bases
- strands separate at the replication fork

Question 13

what is step 2 of DNA replication?

Answer 13

complementary base pairing:
- free nucleotides (from nucleoplasm) move to pair up with exposed bases of each template strand
- hydrogen bonds form between A&T and C&G

Question 14

what is step 3 of DNA replication?

Answer 14

join adjacent nucleotides:
- sugar phosphate backbone forms when DNA polymerase forms covalent bonds between newly attached nucleotides
- result in 2 identical DNA strands

Question 15

what is step 4 of DNA replication?

Answer 15

proof reading:
- DNA polymerase checks for mistakes in copying

Question 16

what direction does replication of DNA occur?

Answer 16

replication only occurs in one direction: from 5’ to 3’

Question 17

what enzymes are needed to form both strands in DNA replication

Answer 17

RNA primase, Ligase, DNA polymerase

Question 18

where does protein synthesis occur?

Answer 18

on the ribosomes in the cytoplasm

Question 19

what molecule cannot leave the nucleus

Answer 19

DNA

Question 20

what is the role of proteins in DNA?

Answer 20

forms structure, drives the processes necessary for life’s functions

Question 21

what are DNA and RNA’s similarities

Answer 21

• both has 4 nitrogenous bases
• both have nucleotide monomers
• both have sugar and phosphate backbone
• Both have A,C,G bases

Question 22

what are the differences between DNA and RNA?

Answer 22

DNA:
-double stranded
- can replicate itself
- cannot leave the nucleus
-contains thymine

RNA:
- single stranded
- contains uracil
- 3 different kinds
- read by ribosomes

Question 23

what are the 2 stages of protein synthesis?

Answer 23

transcription and translation

Question 24

what is protein synthesis?

Answer 24

the process of creating protein molecules

Question 25

what is transcription?

Answer 25

the process of DNA sequence copied into mRNA

Question 26

where does transcription occur?

Answer 26

the nucleus

Question 27

where does translation occur?

Answer 27

the ribosomes

Question 28

what is translation?

Answer 28

the process of mRNA travelling to the ribosomes to link amino acids together with peptide bonds

Question 29

what is step 1 of transcription?

Answer 29

helicase enzyme unzips the DNA strand - starts at initiation region and continues until termination region

Question 30

what is step 2 of transcription?

Answer 30

complementary RNA nucleotides combine to form mRNA strand - joined and re-zipped by RNA polymerase

Question 31

what is step 3 of transcription?

Answer 31

mRNA strand detaches and leaves nucleus through nuclear pores

Question 32

what are codons?

Answer 32

3 letter segments in mRNA

Question 33

what are ribosomes made of?

Answer 33

rRNA and protein

Question 34

where is ribosomal RNA produced?

Answer 34

nucleolus

Question 35

what is tRNA's position in the cell?

Answer 35

floats freely in the cytoplasm

Question 36

what is tRNA's function?

Answer 36

carries amino acid to ribosomes for assembly

Question 37

which molecule contains anticodon?

Answer 37

tRNA contains anticodon complementary to mRNA

Question 38

what is step 1 of translation?

Answer 38

Initiation: -ribosomal subunits join around mRNA - start codon begins the process

Question 39

what is step 2 of translation?

Answer 39

Elongation: - tRNA anticodon and amino acid match up with the mRNA codon - tRNA leaves to collect new amino acids - ribosome moves along to read the next mRNA codon - Peptide bonds form between amino acids

Question 40

what is step 3 of translation?

Answer 40

Termination: - when ribosome reaches stop codon in the mRNA translation stops - ribosome subunits split again and mRNA detaches

Question 41

what is polyribosomes?

Answer 41

(many ribosomes): often several ribosomes work together on one large protein

Question 42

what happens to protein after its produced?

Answer 42

it gets sorted, repackaged, and transported through the endomembrane system