Week 12: DNA Replication & Mitosis 1

Question 1

why is DNA replication referred to as “semi conservative”

Answer 1

because each parental strand serves as a template for the synthesis of a new complementary strand.

the conservative part here refers to the fact that we’re conserving 50% of the original DNA strand in every new DNA strand

Question 2

During replication, DNA is synthesized in the ________________ direction ONLY

Answer 2

During replication, DNA is synthesized in the 5’ to 3’ direction ONLY

Question 3

what is the leading and lagging strand in DNA replication and how do you identify them

Answer 3

Leading Strand:

The leading strand is synthesized continuously in the 5’ to 3’ direction.
DNA polymerase can synthesize the leading strand continuously because it moves in the same direction as the replication fork.

Lagging Strand:
The lagging strand is synthesized discontinuously in short fragments called Okazaki fragments.
DNA polymerase synthesizes the lagging strand in the opposite direction of the replication fork, which means it must synthesize small fragments away from the fork.

How to Identify Them:
If you know the direction of the replication fork (where the DNA is actively unwinding), the strand being synthesized in the same direction as the fork is the leading strand.

The strand being synthesized away from the replication fork is the lagging strand.

Question 4

Question page 7

Answer 4

A. Point A

Question 5

Question page 9

Answer 5

C. CATTG

Question 6

Question page 11

Answer 6

B. Point B

Question 7

Question page 13

Answer 7

E. ACGGG

Question 8

DNA polymerase can only add incoming nucleotides to the _____ side of the growing strand.

Answer 8

DNA polymerase can only add incoming nucleotides to the 3’ side of the growing strand.

page 17

Question 9

what is DNA polymerase and how does it work

Answer 9

enzyme involved in DNA replication

catalyzes the synthesis of a new DNA strand complementary to the existing template strand

Question 10

DNA Polymerase can’t start without ……..

Answer 10

a free 3’ OH group

page 18

Question 11

what is RNA primase and how does it work

Answer 11

RNA primase is an enzyme involved in the process of DNA replication

main function is to synthesize short RNA primers that provide a starting point for the synthesis of new DNA strands. These primers serve as templates for DNA polymerase, allowing it to initiate the addition of nucleotides and the elongation of the growing DNA chain during replication.

Question 12

mistakes in DNA replication is known as …..

Answer 12

mutations

Question 13

why must phenotypes vary in regard to natural selection?

Answer 13

phenotypes must vary in order for natural selection to cause change over time.

pretty much acts as insurance so species don’t go extinct

Question 14

Where does heritable phenotypic diversity come from??

Answer 14

Genetic mutation

Question 15

what is “Horizontal Gene Transfer”

Answer 15

is a way of gene transfer done by prokaryotes since they reproduce asexually

◦ Horizontal gene transfer is a separate process from mitosis / replication / reproduction

Question 16

what is another term for “Outcrossing”

Answer 16

sexual reproduction

Question 17

how does sexual reproduction create diversity

Answer 17

sexual reproduction, combines genes from two sources, creating genetic diversity.

Genetic diversity leads to phenotypic diversity, or a range of traits.

Question 18

how does diversity provide a form of insurance

Answer 18

a range of phenotypes provides opportunities for at least some individuals to succeed under new regimes of natural selection.

Question 19

can natural selection reduce genetic diversity

Answer 19

yes

Question 20

what increases genetic diversity quicker sexual reproduction or asexual reproduction

Answer 20

sexual reproduction

Question 21

what is Mitosis

Answer 21

Cell Division for Growth, wound repair or Asexual Reproduction

Process by which cell replicates itself→cell division that results in two identical daughter cells

Question 22

what is Meiosis

Answer 22

Cell Division to Create Gametes for Sexual Reproduction (eggs and sperm)

Question 23

does Asexual Reproduction produce clones of parent

Answer 23

yes

Question 24

how are somatic (“body”) cells are formed in multicellular organisms

Answer 24

Mitosis

Question 25

what are the only cells in the body not produced through mitosis?

Answer 25

gametes (eggs and sperm)

Question 26

what does “N” refer to in Diploid vs Haploid cells

Answer 26

N = number of unique chromosomes in an organism.

Question 27

what does “2N” refer to in Diploid vs Haploid cells

Answer 27

Diploid (2N): Two complete sets of chromosomes(one from mom and one from dad). In humans, the diploid number is 46.

humans have 22 N + 1 sex chromosome, = 23 N. We are 2N = 46.

Question 28

Haploid (N):

Answer 28

Haploid (N):

One complete set of chromosomes. In humans, the haploid number is 23.

humans have 22 N + 1 sex chromosome, = 23 N

Question 29

briefly summarize the Mitosis Stages in terms of interphase, G1 phase, S phase, G2 phase, Mitotic phase etc…

Answer 29

Interphase: period of growth and preparation,

G1 Phase (Gap 1): The cell grows and carries out normal metabolic functions. It prepares for DNA replication.

S Phase (Synthesis): DNA synthesis occurs, resulting in the replication of the entire genome.

G2 Phase (Gap 2): The cell continues to grow and prepares for mitosis. It synthesizes proteins and organelles.

Mitotic Phase (Prophase, Metaphase, Anaphase, Telophase): involves the actual division of the cell’s genetic material and subsequent separation into two daughter cells.

Question 30

Do question on page 36