Genetics Flashcards
Sex linked recessive :
color blind, hemophilia, muscular dystrophy
autosomal dominant disease
huntington’s
Autosomal dominant tipoff
affected individual has affected parent.
’failure of penetrance’
dominant gene does not express. often happens with syndactyly in parents and then it expresses in child
X-linked dominant example
CGH- hypertrichosis- lots of extra hair on your face- expresses in all the females.
- Characteristic feature of x-linked recessive; expressed more frequently in boys b/c they are____ meaning that _____
hemizygous. if they had a copy of the bad gene, it is not masked by Y, always expressed
atavistic trait
ancestral trait. ex: hair on face, tails
only possibly Y-linked trait
hairy ears.
If more males in a pedigree, the gene inheritance pattern is probably ___ , and recessive. More females- probably ___. Same: probably autosomal
sex-linked
x-linked dominant
if individuals do NOT have affected parents, disease is :
Autosomal recessive
Linked genes
on the same chromosomes. Linkage group: all these genes located on the same chromosomes. affected in crossing over.
phenylketonuria:
missing the enzyme that normally converts phenylalanine to tyrosine- > autosomal recessive disorder -> damage to developing brain-> metabolites spill over into urine. Infants severely mentally retarded ,often die. If you catch it early enough , put them on a phenylalanine free diet, they develop normally. After their brain finishes developing as an adult, they can eat anything. all newborns in the US are screened for PKU.
Achondroplastic dwarfism
- achondroplastic dwarfism is dominant and the most common types of dwarfism.
Primordial dwarfism
7 lb woman
give examples of common dominant genetic traits you’ll see around the classroom
- Widow’s peak: dominant
- Freckles: dominant
- Dimples: dominant
- Brachydactyly:
short stubby fingers + intellectual challenges. Autosomal dominant
Polydactyly:
more than 5 fingers. Classic 6th finger pointing off of pinky.
Marfan syndrome
connective tissue problem. Causes problems with collagen deposits in cells, connective tissue in aorta wall. If you have it, aorta will become really stretched out, so sometimes the walls of your aorta burst unexpectedly.
People normally tall, thin, super long fingers.
When genes are found on different chromosomes or far apart on the same chromosome, they assort independently and are said to be ___
unlinked
When genes are close together on the same chromosome, they are said to be linked. That means that:
the alleles, or gene versions, already together on one chromosome will be inherited as a unit more frequently than not.
how can recombination frequency be useful to us?
shows us if genes are linked
linkage maps
show the order and relative distances of the genes on the chromosome.
When genes are linked, genetic crosses involving those genes will lead to:
ratios of gametes (egg and sperm) and offspring types that are not what we’d predict from Mendel’s law of independent assortment.
When genes are on the same chromosome but very far apart, they assort independently due to
crossing over (homologous recombination).
what exactly does the linkage mean during crossing over?
Instead of assorting independently, the genes tend to “stick together” during meiosis.
Recombinant
new formation of genes that was not present in the original parents
Parental type
combinations of genes that are identical to what one of the parents were
Why are the recombinant gamete types rare?
crossovers between two genes that are close together are not very common
which will happen more frequently: crossovers between genes close together or spaced further apart?
further apart
T/F: recombination frequency is a direct measure of distane apt on the gene
false. we can say that a pair of genes with a larger recombination frequency are likely farther apart, while a pair with a smaller recombination frequency are likely closer together together.
at what recombination frequency can we say genes are not linked?
50%
does protein carry any genetic information?
no- only DNA does
what experiment was Acetabularia?
exchanged caps between individuals from two species, A. mediterranea and A. crenulata.
After the exchange, each transplanted cap gradually changed from its original form to the form typical for the species of the base it was now attached to. This showed that the nucleus controlled the form of the cap.
Griffith-Avery experiment
- 2 types of bacteria. One ‘s’ strain kills mice. R strain does not.
- Took some S strain, heat it up and kill it- mice live.
- Some heat killed smooth ones + rough ones: mice die! Some factor that comes from the heat killed ones and transforms the R’s into S’s.
- Griffith coined the term ‘the transforming factor.’ Some bacteria can take up naked DNA (transformation in bacteria!)
Avery, MacLeod & McCarty
took cultures of heat-killed S cells and progressively purified the transforming principle by washing away, separating out, or enzymatically destroying the other cellular components.
hypothesis: genetic material of cell is either protein or DNA
conclusion: transformation requires DNA therefore it is genetic material of cell
Hershey and Chase experiment
used bacteriophage, or viruses that attack bacteria, inject cells.
- S35 to label proteins (only found in meth, cysteine)
- P32 Phosphorous to label DNA (only found in DNA)
concluded that DNA, not protein, was injected into host cells- only see phosphorus in pellet- and made up the genetic material of the phage.
to which end of DNA is the new strand added?
Nucleotides ALWAYS ADDED AT 3’ end of original strand
T/F: eukaryotes have more than one replication origin?
True