chromosomes Flashcards
what are the 5 main features of a chromosomes structure?
telomere
centromere
2 linear chromatids
euchromatin
heterochromatin
where on the chromosome is the telomere and the euchromatin located
telomere is the tip of the chromatids
euchromatin is just below the telomere
what causes the end-replication problem to occur?
when DNA is replicated it looses 100 base pairs
which enzyme is used to fix the end-replication problem during DNA synthesis
telomerase
state the 4 steps of mitosis & the additional step at the end
prophase
metophase
anophase
telophase
(pass me another tequilia)
cytokinesis -additional step
what end does DNA replication start with always
5’ end to 3’ end (leading strand)
what enzyme helps with DNA replication
DNA polymerase
what type of fragments are produced when the lagging strand (3’) starts replication & what enzyme is responsible for fixing this?
okazaki fragments are produced
ligase enzymes fixes it
where on the chromosome is the kinetochore found ?
centromere
Name the 2 types of chromatin
euchromatin;
heterochromatin
what protein is dna packed with?
histones
what are the units called that is packaged with histones and dna
nucleosomes
Name a method that can be used to visualise and map genetic material and also help us better understand an individual’s chromosomal abnormalities.
FISH -fleuroscent in situ hybridization
which type of cells carry out MEOSIS ?
germ cells
what step/s is different in meoisis compared to mitosis
prophase is different in meosis as crossing over occurs here but not in mitosis
what are the names for egg formation and sperm formation?
oogenesis -egg formation
spermatogenesis -sperm formation
give 3 reasons why it is useful for DNA to be packaged
negatively charged dna is neutralised by positively charged histones
dna takes up less space
allows inactive dna to be kept until required
What do the following terms mean with regard to chromosomes when viewing a karyotype:
-metacentric
-sub-metacentric
-acrocentric
metacentric ; p and q appear equal in length
sub-metacentric; p arm is slightly shorter than q arm
acrocentric ; p arm is so short it doesnt have any functional DNA
the p and q arm of a chromosome , what one is long and what one is short?
q- long arm
p- short arm
when does gametogenesis commence in male and females?
in females- it commences during early embroyonic life
males- in puberty
how many gametes are produced per mitosis in females and males?
females- 1 ovum per menstrual cycle
male - 4 spermatids
where is mitchondrial DNA inhertied from, mother or the father?
mitochindrial DNA is inherited from the mother
what happens to X chromosomes in females that doesnt happen to males?
one X chromosome is randomly inactivated
what are the 3 main groups of chromosome abnormality
numerical
mutational
structural
