Genetics Flashcards
2 factors of a disease?
Environment + genes
What processes occur in a 5’ -3’ direction?
Replication and reading of DNA structure
What is the DNA backbone composed of?
Sugar-phosphate
4 bases in DNA?
Thymine
Adenine
Cytosine
Guanine
What happens when DNA strand associates with proteins (name example of type of proteins)?
Histones
It is wound into a chromosome structure
Explain what can happen to DNA in replication and what it’s defect can result in?
Damaged during replication
-Repair mechanisms exist but when these have defects disease occurs
The stages of cell cycle?
G1, S, G2, M, G1
What stage of cell cycle does DNA synthesis take place in?
S phase
What unzips DNA molecule?
DNA Helicase
Which enzyme copies the 5’-3’ strand?
DNA polymerase
Interphase?
Cell is not dividing the stages of cell cycle included in this is S, G0, G1 & G2
Cell grows and is metabolically active
G2?
After DNA replication the cell continues to grow and produce proteins
M phase?
Mitosis checkpoint
Are chromosomes aligned on the spindle
G1?
Cell may increase in size, produce RNA and synthesize protein
S phase?
Period of DNA replication
Going from 2n- 4n in preparation for mitosis
How does DNA polymerase work with Okazaki fragments?
Copies the 3’-5’ strand which DNA ligase joins
Mitosis outcome?
One diploid cell becomes two identical daughter diploid cells
Meiosis outcome?
One diploid parent cell becomes 4 haploid daughter cells
- crossing over occurs to produce variation
- Gamete formation
Describe an RNA strand?
- Single stranded
- Ribose sugar
- Uracil replaces thymine
Brief description of DNA-> protein?
DNA | Transcribing and splicing RNA | Translation Protein
In detail transcription and translation?
- DNA transcribed to pre-mRNA
- Pre-mRNA pliced (removal of introns) to form mRNA
- mRNA translated to protein (3 bases= 1 amino acid/stop codon)
- Protein is modified and moved around cell
Types of sequence variations within a gene?
Changes in promoter sequence
Changes in exon sequence
Types of sequence changes in DNA between genes?
SNP’s
Larger deletions/duplications
What is a polymorphism?
Any variation in the human genome which has a population frequency of <1%
A polymorphism will cause disease. True or false?
FALSE
It can cause a disease but not in it’s own right, may predispose to a common disease
What is a mutation?
Gene changes that cause a genetic disorder
-any heritable change in the human genome
How many mutations required in a classical genetic disease?
One mutation sufficient to cause disease
Describe multifactorial disease and it’s relation to polymorphisms?
Multiple polymorphisms cause a risk of disease
Chromosome make up of a normal female?
46XX
What consists of an unbalanced chromosome rearrangement?
- Extra or missing chromosomal material
- Usually 1 or 3 copies of some of the genome
- Concerning for development
Aneuploidy?
Whole extra or missing chromosome
Translocation?
Rearrangement of chromosomes
Describe genome defect of Down syndrome in a boy?
Trisomy 21
47XY + 21
What would happen if a genome was 47XY + 14? and what is the formula to describe this?
MIscarraige
Trisomy 14
What is the genome for Edward’s syndrome?
Trisomy 18
47 XY + 18
Which genetic condition is 45X?
Turner’s syndrome