Meiosis and DNA replication

Question 0

What is the overall purpose of meiosis

Answer 0

Reduces the number of chromosomes by half to produce haploid gametes that have 1 copy of each chromosome.

Question 1

What 2 processes does sexual reproduction involve?

Answer 1

Meiosis and fertilization.

Question 2

How many cell divisions are there in meiosis and what do they involve?

Answer 2

2- each involves PMAT,

During the first, the chromosomes are halved, the second- chromosome number stays the same.

Question 3

How is genetic diversity achieved?

Answer 3

Crossing over and random alignment of maternal and paternal homologous during metaphase

Question 4

Describe how chromosomes behave in meiosis

Answer 4

Meiosis I- cells are duplicated in prophase(sisters) spectate in anaphase
Meiosis II- don’t duplicate,sisters are separated into two more daughter cells.
End result- 2 daughter cells each having unique info

Question 5

How are mitosis and meiosis different in terms of end result?

Answer 5

Mitosis: 2 genetically identical daughter cells each with 46 chromosomes
Meiosis: 4 genetically different daughter cells with 23 chromosomes each.

Question 6

Give three examples of checkpoints in meiosis

Answer 6

Spindle assembly checkpoint- before anaphase
DNA damage checkpoint- G1
DNA replication checkpoint-G2

Question 7

Describe the roles of cycling and cyclin dependent kinases in meiosis

Answer 7

Cycling bind to and active cyclin dependent kinases which phosphorylase target proteins to promote cell division

Question 8

How does DNA structure relate to replication?

Answer 8

Consist of 2 anitparallel strands each with identical DNA

Question 9

Explain why replicating the tips of chromosomes is problematic

Answer 9

During the sunthesis of the lagging strand, a number of base pairs are not replicated resulting in a 100 base pair gap which is restored by telomerase.

Question 10

Name the steps of PCR

Answer 10

Denaturation creating 2 individual strands
Annealing of primers to complimentary sequence on DNA strand
Elongation of parental DNA strand

Question 11

How do the properties of DNA determine how it will move through the agarose gel?

Answer 11

Moves toward + end

Longer strands are slower

Question 12

How are DNA molecules sequenced

Answer 12

Fragment DNA into small pieces(100-200)
Add 1000 primers
Replicate DNA
Align fragments with computer

Question 13

Describe several types of sequences found in the genome

Answer 13

Dispersed- repeated nucleotide throughout DNA
Simple-2 nucleotides
Tandem-repeated one after another

Question 14

Describe the purpose of genome annotations

Answer 14

Allows you to find DNA that encodes for a protein or functional RNA

Question 15

What are some small scale mutations?

Answer 15

Point mutations( sense or nonsense)
Small insertions or deletions 
Transposions

Question 16

What is a point mutation

Answer 16

Single nucleotide change

May or may not cause change depending on the location of the nucleotide in the codon

Question 17

Describe small insertion or deletion mutations

Answer 17

Insertion or deletion of nucleotide
Not as big a deal if in multiples of 3- just add or gain codon.
Worse if not a multiple of 3- causes frame shift.

Question 18

What is a transposon mutation ?

Answer 18

Movable sequence that insert themselves into DNA - can cause large interruption in transcription

Question 19

What are some large scale mutations?

Answer 19

Always chromosomal
Duplications and deletions
Trans locations

Question 20

Describe a deletion or duplication in a chromosome

Answer 20

Duplications are less harmful that deletions.

Question 21

Describe an inversion in a chromosome

Answer 21

Giant segment of Chromosome is flipped. May lose function

Question 22

Describe a translocation in a chromosome

Answer 22

Piece of 1 chromosome is stuck to another

Question 23

What happens in prophase 1 of meiosis

Answer 23

Lasts for days

DNA condensed and crossing over occurs before homogous chromosomes are reassembled.

Question 24

What are the steps of DNA replication?

Answer 24

1. proteins open DNA and break h bonds
2. SSB coat DNA to keep it open
3. helicase unwinds DNA
4. RNA primate makes short pieces of primer
5. DNA polymerase synthesizes DNA
6. RNA primers removed.
7. Okazaki France’s sealed.

Question 25

What direction does the DNA sequence grow in?

Answer 25

5’-3’

Question 26

How does DNA polymerase know if an error is made?

Answer 26

H bonds don’t form correctly between base pairs. Incorrect base pairing.

Question 27

How does sexual reproduction cause variation?

Answer 27

Reshuffling of genetic information in every generation.

Question 28

Explain what it means to be diploid

Answer 28

Genetic information is halved in each gamete

Meiosis reduced 2 copies of each gene to 1 copy in our gametes.

Question 29

What is the goal of meiosis

Answer 29

Preserve chromosomes

Create variation- random variation so chromosomes and crossing over to create recombinant chromosomes.

Question 30

What are homologs chromosomes?

Answer 30

Contain the same order of genes but can have different versions
Abcdef
ABCDEF

Question 31

When do cells become haploid in meiosis?

Answer 31

At the end of anaphase 1

Question 32

Which direction are leading

and lagging strands synthesized?

Answer 32

Leading- same direction as fork

Lagging- opposite

Question 33

What is one thing that signals to the cell to stop dividing?

Answer 33

After 50 to 100 mitosis the telomeres get too short.

Question 34

What’s one way cancer continues growing?

Answer 34

Expresses telomerase allowing telomeres to grow