Genetics and Disease Midterm 1 Flashcards
Inheritance pattern and gene affected in hypercholesterolemia?
Autosomal dominant and mutations on LDLR gene
What does LDL-R do?
Binds ApoB 100 to LDL to allow it to transport through the blood stream
For alzheimer, what is the location for APP and PSEN 1?
APP- 21q11, PSEN1 14q24.2
What type of inheritance is alzheimers?
Autosomal dominant
What is the problem with Tay-Sachs
There is a deficiency of Hexoaminidase A that leads to accumulation of gangliosides in the central nervous system
Tay-Sachs is biochemically considered to be _
Incomplete dominance
How is hemophilia inherited?
X-linked recessive
How is fragile x syndrome inherited?
X-linked dominant
What gene has the mutation with fragile x?
FMR-1 gene is mutated
How do you inherit cycstic fibrosis?
Autosomal Recessive
What gene has the mutation for cystic fibrosis? And what does that cause?
CFTR gene, causes water accumulation because Cl cant move
What is the deletion for cystic fibrosis?
Delta F 508, deletion of phenylalanine
What is special about a compound heterozygote?
More severe than a heterozygote, less severe than a homozygote recessive
Which strand synthesizes okazaki fragments?
In the lagging strand
What are the 3 phases of DNA replication?
Initiation, elongation, termination
What happens in initiation?
Proteins bind to DNA, open the double helix and prepare DNA
What happens in elongation?
Proteins connect the sequence of nucleotides into a continuous strand of DNA
What happens in termination?
Proteins release from the replication complex
Topoisomerase:
Prevents torsion/breaks
Helicase:
Separates 2 strands of DNA
Primase:
Synthesizes RNA primers
Single strand binding proteins:
Prevents reannealing of single strands
DNA ligase:
Seals nicks in DNA
DNA pol:
Synthesizes DNA, also functions as exonuclease in eukaryotes
What is telomerase and what cells have it?
Telomerase restores telomere length to avoid loss of DNA at the end where the RNA primer was, only present in stem cells and cancer cells
What are the short RNA sequences that DNA pol needs to function?
RNA primers
What are the 3 types of DNA?
Nuclear DNA - coding, Extragenic/junk DNA - noncoding, Mitochondrial DNA - rRNAs and tRNAs
What are single copy genes?
most genes like CFTR, insulin, growth horomone
What are multi gene families?
Arose through duplication of one gene
Classic gene families:
overlapping functions
Gene superfamilies:
non overlapping functions
What is a cluster of genes called and what chromosomes are they on?
globin or globin chain found on chromosomes 11 and 16
what causes a globin?
duplication and mutation
What are microsatelites?
2-4 bp 10-30 repeats, rarely on coding genes and can cause disease
What are minisatellites?
6-100 bp up to 1k repeats, telomeres
What are satellites?
several hundred bp, clustered around centromeres
What are tandem repeats? Length and what affects them?
Short-medium length sequences repeated in tandem. Affected by error during replication
What is a TE or transposon?
A DNA sequence that can change its position within a genome
How much of the genome are Transposable elements?
one third of the genome
Who discovered transposable elements?
Barbara mclintock and earned nobel prize in 1983
What are the two main types of transposable elements?
DNA transposons and retrotransposons - from RNA and use reverse transcriptase
What are SINEs and what kind of transposons are they?
Short interspersed Nuclear elements that are Alu sequences ~300bp retrotransposons
What is an SNP?
Single nucleotide polymorphism
replacing, deleting or adding a nucleotide base
What is a synonymous mutation?
Codon is changed but the amino acid is the same
When is a missense mutation conservative and nonconservative?
Conservative if replaced with a similar AA nonconservative if replaced with a different AA
What is a nonsense mutation?
Introduces a premature stop codon - truncated protein
What does SNP splice site result in
Results in intron retention or exon skipping
How many base pairs are indels usually?
1-3 bp
What can indels cause?
frameshift, like Phe deletion
What is the result when DNA pol slippage forms a loop in template? In new DNA?
Template - DNA deletion, new DNA - DNA insertion
What diseases can Alu cause?
Insertion, coag factor IX deficiency, recombination- familial hypercholesterolemeia
Structural polymorphisms?
Duplication, inversion, ind/el, translocation
What are the 3 kinds of Loss of Function mutations?
Reduced activity, loss of protein, haploisufficiency
How is loss of protein inherited? What does it mean?
Recessive. The presence of 1 functional copy = healthy
What is haploinsufficiency? How is it inherited?
One copy is not enough to be healthy. Dominant inheritance
What is a gain of function mutation? How is it inherited?
Increased gene expression or new function. Often dominantly inherited
What is a Dominant-Negative mutation?
Heterozygote has loss of function as a mutation and interferes with the function of a normal gene product.
What causes Chronic Myeloid Leukemia?
Reciprocal translocation from chromosome 22 to 9 - philadelphia chromosome
What is Robertsonian translocation?
2 acrocentric chromosomes break and the q arms join.
What issues does robertsonian translocation cause?
It causes issues at meiosis. Monosomies or down syndrome
What is a gene?
The biological unit of heredity
Alleles:
alternate forms of a particular gene.
What is a trait? Example?
A variation of a character. Eye color is character and blue eyes are the trait
What is a locus?
the location on a gene/chromosome
What is a haplotype block?
Segments of DNA that do not undergo recombination.
What is a hotspot?
Segements of DNA that are prone to recombination and allow the shuffling of haplotype blocks
What is a haplotype?
A set of alles of different genes that are closely linked on one chromosome and are usually inherited as a unit.
How is Duchene Muscular Dystrophy inherited?
X-linked recessive
Where is the dystrophy gene for DMD?
Xp21
Gower’s sign is related to ?
DMD
Acrocentric
No coding genes on little arms
Submetacentric
Centromere is almost in the middle
Metacentric
Centromere is in the middle can you can distinguish p and q arms
