Chapter 6 & 7 Flashcards
What is a pedigree?
a chart that tracks which members of a family have a particular trait
What four different patterns will a pedigree reveal?
- autosomal recessive
- autosomal dominant
- X-linked recessive
- X-linked dominant
What is X-linked recessive?
How can you tell if a pedigree shows this?
- A gene located on the X-chromosome
signs:
- more affected males
- affected males only pass trait to their daughters
- unaffected carrier mothers produce affected sons
What is X-linked dominant?
How can you tell if a pedigree shows this?
- Much more severe effects in males
signs:
- affect father passed trait to all of his daughter
- no sons are affected unless mother is
How can you tell if a pedigree shows autosomal recessive?
signs:
- trait skips generations (affected individuals with carrier parents)
- equal male-female ratio
How can you tell if a pedigree shows autosomal dominance?
signs:
- trait doesn’t skip generations
- equal male-female ratio
What are the two types of twins?
- monozygotic
- dizygotic
What are monozygotic twins?
- identical twins
- a zygote splits into two separate masses of cells, and develops into a separate embryo
- share genes, not environment
What are dizygotic twins?
- non-identical twins
- 2 ovum at the same time
- different genes, same environment
What is concordance?
the occurrence of the same clinical condition in both members of a twin pair
What is genetic counseling?
- process that identifies potential genetic risks
- use of family pedigree
- helpful in the family planning process
What is linkage?
the tendency for loci to be inherited together
Why would loci be inherited together?
they are physically close on the same chromosome
What is no linkage’s ratio?
9:3:3:1
What is a two-point test cross?
heterozygous crossed with homozygous recessive
What is coupling?
What is it called?
What is the ratio?
- when 2 dominant alleles are on a chromosome and 2 recessive alleles are on another
- cis configuration
- 4:1:1:4
What are parental genes (non-recombinant?
chromosomes that carry similar genes from two different parents
What are recombinant chromosomes?
a chromosome that carry genes derived from two different parents
What is repulsion?
What is it called?
- when A and b are on one chromosome and a and B are on another
- trans configuration
Repulsion:
What are(is) the percentage(s) for:
Independent assortment
- AaBb
- aabb
- Aabb
- aaBb
Complete linkage
-AaBb
- aabb
Linkage with cross-over
- AaBb
- aabb
- Aabb
- aaBb
Independent assortment
- all 25%
Complete linkage
- all 50%
Linkage with cross over
- all 25%
What is complete linkage?
2 loci are so close together in the same chromosome that there is no crossing over
With complete linkage, is there recombination?
no
How might there be recombination with complete linkage?
if 2 loci have just enough spacing inbetween
What is genetic mapping?
The process of determining the location and chemical sequence of specific genes on specific chromosomes.
Morgan and his students hypothesized that the probability of crossing over between linked loci should be proportional to the actual ___ ___
physical distance
How do you calculate the frequency of recombination?
the total recombination divided by the total offspring
If two crossing over events occur between two loci, they will cancel each other out, and there is no ___
recombination
Shorter distance is ___ than longer distance for mapping
better
What are the advantages of the three-point test cross?
- fewer crosses are needed
- some double cross overs are detected
What are genome-wide association studies?
A large-scale analysis of the genomes of many people having a certain phenotype or disease
- aim to find genetic markers that correlate with that phenotype or disease.
What is a haplotype?
A group of gene or DNA variations that exist on the same chromosome and are likely to be inherited together.
What does crossing over disrupt?
What does it cause?
- length of mutant haplotype region get shorter
- different lengths in different families
What are genetic markers?
Genetic abnormalities found in some people that predict the odds of having certain types of cancers.
What is Single Nucleotide Polymorphism (SNP)?
It is a common single base substitution between individuals. Rare single base substitutions are called mutations.
What is deletion mapping?
- to find where transcription factors bind
- make a series of different deletions and see where activation stops.
The bigger of a deletion the ___ loci disappear
more
What is somatic cell hybridization?
What is it called?
-type of physical gene mapping
-fuses two cells. The chromosomes begin to degrade throughout cell lines and can be used to determine which chromosome contains a gene of interest
- heterokaryons
What are recombination hotspots?
Small regions of the genome that are particularly prone to serving as locations of crossover.
