Meiosis and DNA replication Flashcards
What is the overall purpose of meiosis
Reduces the number of chromosomes by half to produce haploid gametes that have 1 copy of each chromosome.
What 2 processes does sexual reproduction involve?
Meiosis and fertilization.
How many cell divisions are there in meiosis and what do they involve?
2- each involves PMAT,
During the first, the chromosomes are halved, the second- chromosome number stays the same.
How is genetic diversity achieved?
Crossing over and random alignment of maternal and paternal homologous during metaphase
Describe how chromosomes behave in meiosis
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
How are mitosis and meiosis different in terms of end result?
Mitosis: 2 genetically identical daughter cells each with 46 chromosomes
Meiosis: 4 genetically different daughter cells with 23 chromosomes each.
Give three examples of checkpoints in meiosis
Spindle assembly checkpoint- before anaphase
DNA damage checkpoint- G1
DNA replication checkpoint-G2
Describe the roles of cycling and cyclin dependent kinases in meiosis
Cycling bind to and active cyclin dependent kinases which phosphorylase target proteins to promote cell division
How does DNA structure relate to replication?
Consist of 2 anitparallel strands each with identical DNA
Explain why replicating the tips of chromosomes is problematic
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.
Name the steps of PCR
Denaturation creating 2 individual strands
Annealing of primers to complimentary sequence on DNA strand
Elongation of parental DNA strand
How do the properties of DNA determine how it will move through the agarose gel?
Moves toward + end
Longer strands are slower
How are DNA molecules sequenced
Fragment DNA into small pieces(100-200)
Add 1000 primers
Replicate DNA
Align fragments with computer
Describe several types of sequences found in the genome
Dispersed- repeated nucleotide throughout DNA
Simple-2 nucleotides
Tandem-repeated one after another
Describe the purpose of genome annotations
Allows you to find DNA that encodes for a protein or functional RNA
What are some small scale mutations?
Point mutations( sense or nonsense) Small insertions or deletions Transposions
What is a point mutation
Single nucleotide change
May or may not cause change depending on the location of the nucleotide in the codon
Describe small insertion or deletion mutations
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.
What is a transposon mutation ?
Movable sequence that insert themselves into DNA - can cause large interruption in transcription
What are some large scale mutations?
Always chromosomal
Duplications and deletions
Trans locations
Describe a deletion or duplication in a chromosome
Duplications are less harmful that deletions.
Describe an inversion in a chromosome
Giant segment of Chromosome is flipped. May lose function
Describe a translocation in a chromosome
Piece of 1 chromosome is stuck to another
What happens in prophase 1 of meiosis
Lasts for days
DNA condensed and crossing over occurs before homogous chromosomes are reassembled.
