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GENETICS FINAL EXAM
Terms in this set (64)
Genic sex determination
Instead of there being a defining difference between the chromosomes themselves, the sex of an organism is determined by the genotypes at one or more loci.
The small regions in which the X and the Y chromosomes are homologous (carry the same genes); these cause of the pairing of said chromosomes during meiosis.
ZZ-ZW sex determination
System used to determine sex in birds, snakes, butterflies, some amphibians, and some fish.
Females are ZW (Ze Woman!)
Males are ZZ (Men sleep)
Sex determination in Drosophila
Determined by finding a ratio by dividing the number of X chromosomes by the number of sets of haploid autosomes.
Female = 1.0
Intersex= 0.67 (XX; AAA)
XX-XO sex determination
Found in insects.
Females have XX; males have XO.
When two different gametes are produced in the sense that they contain two different sex chromosomes (or the absence of one)
When two identical gametes are produced in the sense that they both contain the same sex chromosome.
Genotype: XO (Think hugs and kisses. O=hUg; TUrner is the only syndrome with a u in it)
Phenotype: Short; low hairline; broad chest; neck folds
(When thinking about the phenotypes think "AYEEE TURNER BACK AROUND" because you don't to be looking at all that ugly shit she got going on in the front. Also Timmy Turner was short)
Gender: Male (Calvin CLINE is male)
Genotype: XXY, XXXY, XXXXY
Phenotypes: tall, small testes, reduced facial pubic hair
If a cell contains 2 or more X chromosomes, all but one of them will be inactivated.
Ex. Tortoise-shell and Calico cat coats
There is an intermediate between the dominant and recessive phenotype.
Ex. Red + White = Pink
A heterozygous individual will express both phenotypes of the dominant and recessive alleles.
when the genotype does not always produce the expected phenotype
The percentage of the population that have a particular genotype and express the expected phenotype.
The degree to which a trait is expressed.
In polydactyly, where an individual forms extra digits, the extra digits will vary in functionality as well as structural integrity.
For a group on individuals at a particular loci, there exists multiple alleles.
Ex. Blood type
An individual who has two different alleles at a locus which result in a recessive phenotype.
the inhibition/masking of a gene a specific locus by a gene at a completely different locus.
The gene who does the masking.
The gene whose effect is masked.
(Hypo>hypochondriacs wear masks> they are masked)
takes place if an individual possessing two recessive mutations has a wild-type phenotype, which indicates that the mutations are non-allelic (they don't occur at the same locus)
encoded for by autosomal genes that are expressed in only one sex
(the trait has zero penetrance in the other sex)
Genetic maternal effect
phenotype of the offspring is determined by the phenotype of the mother
The differential expression of a gene depending on whether it was inherited from the male or the female parent
Those which don't have many easily distinguished genotypes; ex. skin color
Those which are able to be described in quantitative terms; ex. height
One gene affects multiple characteristics
Number of recombinant progeny/ x100
Total number of progeny
like alleles (dominant or recessive) are coupled on the same chromosome
Double cross-over recombinant progeny
the two groups of progeny that produce the least expected number of progeny
The degree to which one crossover interferes with additional crossovers in the same region.
1 - coefficient of coincidence
(This number X100 gives us the percentage of double crossover progeny that we will not observe due to interference)
Coefficient of coincidence
Number of observed double crossovers/number of expected double crossovers
variable genes with easily observable phenotypes whose inheritance could be studied; used in mapping ex. RFLP
Single-nucleotide polymorphisms (SNPs)
Positions in the genome at which people are vary in a single nucleotide base.
the expression of a normally recessive mutation
when a single copy of a gene is not sufficient enough to produce a wild-type phenotype
What are two effects of deletions in a chromosome?
Pseudodominance and haplo-insufficiency
On one side of the centromere; inversion on heterozygotes leads to aberrant meiosis during cross over and formation of dicentric bridge; recombinant
Includes the centromere in inversion; inversion loop forms during meiosis and causes unequal exchange. Too many genes end up on one gamete and too little on the other.
only one of the chromosomes donates its genetic information
Two-way exchange between the segments of chromosomes
The long arms of two chromosomes join to a common centromere through a translocation creating one long chromosome and one very short chromosome. The short one is often degraded.
One extra or one missing pair of chromosomes
Loss of both members of a homologous pair of chromosomes (2n-2)
Loss of a single chromosome
Occurs when in:
Meiosis I the homologous chromosomes are not separated.
Meiosis II the sister chromatids are separated but end up in the same gamete.
Mitosis small groups of cells can lead to mosaicism.
Exact multiples of haploid chromosome sets for every chromosome
Multiple sets from the same genome; can happen from mitotic non-disjunction (chromatids separate, cell does not divide) or from NDJ in meiosis I (generates triploid organism)
Multiple sets of genomes from different species
Consequences of polyploidy
Bigger nucleus, increase in cell size
Horizontal plane cleavage
αlpha DNA polymerase
primase activity and initiates DNA synthesis by synthesizing RNA primer and lays down nucleotides
delta DNA polymerase
completes replication on lagging strand
epsilon DNA polymerase
completes on leading strand
gamma DNA polymerase
replicates mitochondrial DNA
Vertical plane cleavage
Replicating structure made up of a protein coat surrounding a nucleic acid.
Reproduce stricly through the lytic cycle and kill their host cells.
Can undergo either the lytic or the lysogenic cycle.
Phage binds to host cell; injects DNA; host DNA is digested; phage DNA is transcribed and translated by the host cell producing phage proteins; new phages are released to start the cycle again
Phage attaches to host and injects DNA; phage DNA and host DNA integrate and become a prophage; the prophage replicates many times through cell division; the host and phage DNA may separate and the cell would go through the lytic cycle.
Joshua Lederberg and Edward Tatum
bacteria can transfer and recombine genetic information
U-tube; proved that conjugation was necessary
plasmids that are capable of replicating freely and can integrate into bacterial chromosomes
Ex. fertility factor
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