6: Cell Division Flashcards
DNA replication
what does DNA polymerase do
links nucleotides together, forms new strands using pre-existing strands as a template
catalyses condensation reactions
what happens in prophase 2 meiosis
supercoiling
nuclear envelope disintegrates
mitotic spindles form
what separates VNTR fragments
gel electrophoresis
what is the order of processes in mitosis
(interphase) prophase, metaphase, anaphase, telophase (cytokinesis)
what two things in meiosis promote genetic variation
random orientation
crossing over
The DNA is copied with a high degree of accuracy because
each nitrogenous base can only pair with its complementary partner
Adenine (A) pairs with thymine (T) – via two hydrogen bonds
Cytosine (C) pairs with guanine (G) – via three hydrogen bonds
bivalent
a pair of homologous chromosomes
mitosis produces how many cells and what type
2 diploid
what is random orientation
where the alignment of chromosomes is random
DNA profiling means
individuals can be identified and compared via their respective DNA profiles
what happens after telophase 2 meiosis
cytokinesis
what is nondisjunction
occurs when chromosomes fail to separate during anaphase one or two, resulting in gametes with an abnormal about of chromosomes
what sort of cells and how many does meiosis make
haploid, 4
what phase does DNA replication happen
s phase
what is the chiasma
is the point of crossing over
where the two homologous chromosomes bivalently
Gel electrophoresis is a laboratory technique used to separate and isolate DNA fragments based on
mass/size
what two enzymes are involved
helicase and dna polymerase
what is synapsis
formation of the bivalent
DNA replication is what (one word)
semi conservative
what is it called when there is a third chromosome in number 21
trisomy of the 21st chromosome
which chromosome is associated with downs
21st
rule: any band that appears in the childs profiling, must be present in
either the mother or fathers
DNA can be amplified via
PCR
explain gel electrophoresis
Samples placed in a block of gel and an electric current is applied which causes the samples to move
separate because DNA is negatively charged due to phosphate group
Smaller samples are less impeded by the gel matrix and hence will move faster through the gel
This causes samples of different sizes to separate as they travel at different speeds
when does random orientation happen
metaphase one or two
what happens in prophase mitosis
DNA supercoils and condenses
Nuclear envelope disintegrates
Mitotic spindle forms
what does PCR stand for
polymerase chain reaction
when is the only time a DNA molecule is replicated
when a new cell is required (DNA replication only occurs during the S phase of interphase)
Everyone has repeating non coding regions of DNA that are unique to them called
VNTR’s
what happens in prophase 1 meiosis
DNA supercoil
nuclear envelope disintegrates
homologous chromosomes pair
crossing over
VNTR’s stand for what
variable number tandem repeats
what is commonly related to a child having downs syndrome
maternal age
give 2 examples of unequal cytokinesis
oogenesis
budding in yeast
what happens in metaphase mitosis
chromosomes move into the middle
centrosomes reach opposite poles
when does crossing over occur
prophase 1
oogenesis produces what
produces oocytes and 3 polar bodies
what happens after telophase 1 in meiosis
cytokinesis
what happens in telophase 1 meiosis
nuclear envelope forms
spindles disappear
what is crossing over
exchange of alleles between non sister chromatids of homologous chromosomes
how does cytokinesis happen in plant cells
cell plate forms at equator formed from vesicles
what happens in metaphase 1 meiosis
chromosomes move to the metaphase plate
independent assortment
what happens in anaphase 1 meiosis
separation of homologous chromosomes
what type of enzyme chops the DNA in gel electrophoresis
restriction enzymes
PCR technique can be used to
to amplify large quantities of a specific sequence of DNA from an initial minute sample
what does helicase do
unwinds the dna, causes hydrogen bonds to break between pairs, exposing bases
what happens in anaphase 2 in meiosis
sister chromatids move to opposite poles
DNA can be separated via
gel electrophoresis
what happens in interphase mitosis
growing and making copies of DNA
(DNA is not condensed)
what happens in interphase meiosis
DNA replication
DNA not condensed
what is the name for the gap beginning to form in cytokinesis
cleavage furrow
what happens in anaphase mitosis
sister chromatids move to opposite poles
what happens in telophase 2 in meiosis
nuclear envelope forms
spindles disappears
why does DNA replication need to happen?
to prepare a cell for mitosis/ cell division
name 3 applications of electrophoresis and PCR
DNA profiling
Gene cloning involves the use of these techniques to insert genes of interest into different species
Sequencing uses these techniques to determine specific DNA sequences
what does semiconservative mean
One strand will be from the original template molecule (conserved)
One strand will be newly synthesised (not conserved)
what does crossing over occur between
homologous chromosomes
what is the first step of PCR
Denaturation – DNA sample is heated (~90ºC) to separate the two strands
what is the second step of PCR
Annealing – Sample is cooled (~55ºC) to allow primers to anneal (primers designate sequence to be copied)
what are 5 requirements for a PCR
1) the target DNA or RNA being amplified
2) section identified by adding a primer sequence
3) taq polymerase
4) free nucleotides for constructing strands
5) buffer solution for optimum pH
what happens in metaphase 2 meiosis
chromosomes move to metaphase plate
what happens in telophase mitosis
nuclear envelope forms
spindles disappear
Chromosomes decondense
why is taq polymerase used
doesn’t denature at high temps
what is the third step of PCR
Elongation – Sample is heated to the optimal temperature for a heat-tolerant polymerase (Taq) to function (~75ºC)
