bio exam 4 Flashcards
Darwin’s Heredity Theory
Little “Bits” (gemmules) of each trait aggregated in the gamete to form an offspring
The Blending Hypothesis
Traits from each parent mixed together and the offspring is a perfect mix of he 2 parents
Gregor Mendel
monk
mathematician
pea plants
enginerr
Monohybrid Cross
Crossbreeding two organisms in reference to a specific trait
True Breeding
Only produces 1 of the 2 traits possible over many generations
Mendel established
the dominant and recessive relationship between traits
Genotype
what gene you are carrying :
AA- Homozygous Dom
Aa- Heterozygous
aa- Homozygous recessive
Phenotype
The physical manifestation of the genotype
Incomplete Dominance
The dominant allele determines how much of a gene you have. If mom is white and dad is red, then Aa could show up as pink
Co-Dominance
When two or more dominant alleles are present in one trait Ex: AB blood type
Pleiotropy
One gene at one locus WITH IT’S OWN INDEPENDENT PHENOTYPE, affects the expression of another gene at another locus
Epistasis
One gene at one locus WITHOUT IT’S OWN INDEPENDENT PHENOTYPE, affects the expression of another gene
Y chromosome:
- has 75 genes on it
- All about sexual reproduction and secondary sexual characteristics
X chromosome:
- has 1000 genes
- MOST are about sexual reproduction and secondary sexual characteristics
- SOME sex linked genes are not about sexual reproduction and secondary sexual characteristics
Some recessive disorders are sex-linked:
Men are more likely to show sex-linked recessive disease because they only have 1 X chromosome and must show whatever that chromosome carries
Carriers must be heterozygous, so what is the only gender that can be a carrier
women
X-inactivation
In the Autosomal/non-sex/somatic cells. one X is randomly activated.
Mosaicism
Each cell displays traits on only one X
Klinefelter’s
XXY ( extra X from mom = nondisjunction)
Polygenic
Many genes affect one characteristic
if A = 10% then….
T= 10%
C= 40%
G= 40%
Origin:
Where the enzymes respawn for duplication bind at the chromosome
At the origin,
- 2 strands are separated, forming the replication bubble
The ends of the replication bubble are called
Forks
Replication proceeds away from:
the origin into the forks in both directions.
When 2 bubbles meet they….
form together
When replication is complete,
the 2 daughter DNA mols each consist of an old strand and a new strand
What are the 7 enzymes in replication/duplacation
Helicase, Topoisomerase, Single stranded binding proteins, Primase, DNA polymerase 3, DNA Polymerase 1, and Ligase
Helicase:
- breaks hydrogen bonds
- unwinds the helix (creates a knot in the DNA)
- unzips the double strand
Topoisomerase
- relieves tension from helicase
- Cuts off the knot and heals the cut
Single Stranded Binding Proteins
- follows helicase and prevents the 2 strands from rezipping
Primase
initiates replication by building a short RNA primer at the origin
DNA polymerase 3
- builds the new complementary DNA strands by adding to the primers
- Can only build from 5’ to 3’
Leading strand
- Runs from 5’ to 3’
- quick and easy to build
-runs into the replication fork
Lagging strand
- Runs from 3’ to 5’ into rep fork
- Difficult to build
- Primase builds multiple primers along the lagging strand
- DNA poly 3 fills in between the primers in the opposite direction
Okazaki Fragments
The short segments of DNA between the primers on the lagging strand
DNA Polymerase 1
- Removes RNA nucleotides and replaces them with DNA nucleotides
Ligase
- Follows DNA poly 1 to check that DNA’s polymerase nucleotides
