2. Replication and Mendelian Inheritance I

Semi-conservative replication

in each new DNA double helix, one strand is from the original molecule, and one strand is new

What 5 things do you need for DNA replication

1. dNTPS (special type of nucleotide used during replication)

2. DNA polymerase (catalyzes DNA synthesis)

3. DNA template

4. DNA/RNA primer

5. Mg 2+ for polymerase activity

New DNA is made in what direction

5' to 3'

Replicator

A sequence of DNA that denatures (opens up) to form the replication bubble. It's where REPLICATION STARTS.

Where replication starts is called the

origin of replication

the denatured area where replication is happening is called the ________ and in it is the ________

replication bubble

replication fork

Step 1 of DNA Replication

Initiation:

- RNA primer made by DNA primase starts replication of lagging strand (synthesis of 1st okazaki fragment)

Step 2 of DNA Replication

Further untwisting and elongation of new DNA strands, 2nd okazaki fragment elongated.

Step 3 of DNA Replication

Process continues until entire strand is copied

Step 4 of DNA replication

primer removed by DNA polymerase I. When completed, single-strand nick remains.

Step 5

joining of adjacent DNA fragments by DNA ligase.

What stitches together the Okazaki fragments

DNA polymerase I and ligase.

DNA poly I uses the preceding okazaki 5' end fragment to add dNTPS and link it to the next fragment.

Ligase seals the last sugar phosphate backbone bond (called the nick).

Eukaryotes have

multiple origins of replication

telomerase

https://www.youtube.com/watch?v=it8g9RU8KMM

An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells.

It complementary bases to the overhang that's present when the primer is removed.

genotype vs. phenotype

genotype: sequence of bases (genetic composition)

phenotype: appearance (observable traits)

Phenotype depends on 2 things:

genes + environment

What happens when you breed 2 true breeding plants? (one homozygous dominant, one homozygous recessive)

F1: all heterozygous (Pp)

Which alleles are expressed in phenotype

dominant

the sequence of bases for dominant and recessive alleles are

dfferent

ex: the gene for flower color is found on the same chromosome but different sequence of bases at that locus leads to different phenotypes

F2 generation phenotype ratio

3:1

Mendel's Principle of Dominance:

Dominant alleles mask recessive alleles in phenotype. Recessive alleles do not show where dominant alleles are expressed.

Mendel's Principle of Segregation.

What cross shows this

each gamete only carries one allele. So in the gametes of the F1 generation, A separates from a, and when they combine to form F2, you get 3:1.

Production of F1 x F1 = F2 generation: 3:1

Mendel's Principle of Independent Assortment.

Which cross shows this and what ratio do you get

alleles of different genes assort into gametes independently of one another.

Crossing 2 heterozygotes that are heterozygous for both traits (SsYy x SsYy) = 9:3:3:1

9 is dom in both, 3 is dom in one, 3 is dom in another, 1 is recessive in both

Ratio of genotypes vs ratio of phenotypes

ratio of genotypes: heterozygous to homozygous

phenotypes: traits (like smooth: wrinkled)