Genetics Flashcards
what direction is DNA replicated?
5’ to 3’
what is a chromosome made of?
DNA strand that has associated with proteins
what happens in G1 of the cell cycle?
cellular contents, apart from the chromosome, are duplicated
what happens in S of the cell cycle?
DNA replication
what happens in G2 of the cell cycle?
cell undergoes its second growth period and assembles the materials needed for mitosis
what happens in M of the cell cycle?
mitosis
in meiosis, one diploid cell becomes…
4 haploid
in mitosis, one diploid cell becomes
2 diploid
when does crossing over occur?
meiosis
in splicing, what is removed from pre mRNA?
introns (non coding)
what is a polymorphism?
Any variation in the human genome that does not cause a disease in its own right. It may however, predispose to a common disease
what is a mutation?
A gene change that causes a genetic disorder. (a disease causing mutation)
what are the parts of a chromosome?
telomere short arm (p) centromere long arm (q) telomere
what is an acrocentric chromosome?
the short arm (p) is too small to see
what is a metacentric chromosome?
both arms are the same length
what is aneuploidy?
whole extra or missing chromosome
what is a Robertsonian Translocation?
two acrocentric chromosomes stuck end to end (only occurs with 13, 14, 15, 21, 22)
trisomy 21
down’s syndrome
trisomy 18
Edward syndrome
45 X
Turner syndrome
47 XXY
Klinefelter syndrome
what are Reciprocal Translocations?
an exchange of genetic material between non homologous chromosomes (can be balanced or unbalanced)
symptoms of Digeorge Syndrome
- tetralogy of fallout
- thymus problems
- learning difficulties
what is Somatic Mosaicism
two populations of genetically different cells within an individual
what can her2 amplification cause?
breast cancer
what is the Philadelphia chromosome?
a gene translocation in chromosome 22 of cancer cells
7 types of mutations in DNA
wild type stop missense insertion deletion (out of frame) deletion (in frame) triplet expansion
what is Penetrance?
The likelihood of having a disease if you have a gene mutation
pattern of X-Linked Recessive Inheritance?
for females - half male children affected, half female children carriers
for males - no male children affected, all female children carriers
what is X inactivation?
one copy of the x chromosome in females is inactivated
what is methylation and what does it do?
methyl groups added to DNA, it prevents transcription
what is imprinting?
variation in gene expression, depending on which parent you inherit the gene from
what happens in Angelman’s syndrome?
mother’s copy of UBE3A is methylated and does not work
what is Heteroplasmy?
Different daughter cells contain different proportions of mutant mitochondria (similar to mosaicism)
who is mitochondrial DNA inherited form?
mother
what is epigenetic variation?
Functional modifications to the genome that do not involve a change in the nucleotide sequence
where are the checkpoints in the cell cycle?
Between G2 and M
Between G1 and S
how many copies of a tumour suppressor gene are required to be mutated for control to be lost?
2
variation occurs via meiosis by..
Crossing over
Independent segregation of homologous chromosomes
what is a telocentric chromosome?
The centromere is located at the terminal end of the chromosome
