AP Bio - Ch.13: The Molecular Basis of Inheritance (DNA replication)

genes

Discrete unit of Inheritance, made up of DNA and belongs to macromolecule class of nucleic acids

Gene expression

Translation of genotype to phenotype through DNA providing directions for RNA synthesis (through mRNA) where RNA controls protein synthesis

Proteins implement the genotype to be expressed

Polynucleotides

Macromolecule that nucleic acids exist as

Nucleotides

The monomer of polynucleotides

5’C

The ____ end of the DNA strand connects to the phosphate group

3’C

The ___ end of the DNA strand connects to a hydroxyl group

Where DNA strands get elongated from during DNA replication

Anti-parallel

DNA has two strands that are ____ to each other

Meaning: sugar-phosphate backbone arrangement are inverse of each other (subunits, along their 5’ and 3’ ends, run opposite of each other)

Covalent bonds

These bonds hold the sugar-phosphate backbone in DNA together

Hydrogen bonds

These bonds hold the nitrogenous bases of DNA together

Pyrimidines

Five-membered ring nitrogenous base

• (C) Cytosine

• (T) Thymine

  • or (U) Uracil, if it’s RNA

Base-pairs with purines

Purines

Nitrogenous base that is a six-membered ring, fused with a five-membered ring.

• (G) - Guanine

• (A) - Adenine

Base-pairs with pyrimidines

Deoxyribose

The pentase sugar present in DNA

Ribose

The pentase sugar present in RNA

semiconservative model

Model that depicts that daughter DNA from DNA replication will have 1 parental strand and a newly made strand

(Parent DNA splits into two → serves as template strand for 2 separate, new DNA to be duplicated from)

origins of replication

Sites where chromosomal DNA replication begins

Replication fork

End of the bubble where the parental strand is being unwound during DNA replication

Helicase

Enzyme that unwinds the parental DNA at the replication forks

Primase

Enzyme that synthesizes a primer to form

• Primer — hydroxyl group set up at the lagging strand → helps elongate the DNA from the 5’ end

Topoimerase

Enzyme that relieves the strain of the tighter-twisting DNA ahead of the replication fork, due to the DNA unraveling during the DNA replication process

DNA polymerase

Synthesizes new DNA from the 3’C end

DNA ligase

Enzyme that joins sugar-phosphate backbone into one continous strand

Leading strand

New complementary strand of DNA synthesized continuously towards the replication fork in the 5’C to 3’C direction

Lagging strand

New complementary strand of DNA synthesized discontinuously away from the replication fork in 3’C to 5’C direction

mismatched repair

DNA repair that occurs when nucleotide evades polymerase proofreading during DNA synthesis

Nuclease

DNA-cutting enzyme that cuts out portion of damaged strand

Nucleotide excision repair

Repair that involves the cutting out and repairing of a damaged strand through nuclease, polymerase, and a DNA ligase

Telomeres

repetitive nucleotide sequences that acta s “buffer zones” at the ends of chromosomes

Telomerase

enzyme that catalyzes telomeres to lengthen in cells that divide too frequently; can be found in gametes (why gametes still retain their genetic information)

Histones

Proteins responsible for first level of DNA packaging in a protein

Nucleosomes

“beads” seen in unfolded chromatin. Folded, makes the complex chromatin structure

Considered the basic unit of DNA packaging

plasmids

Small circular (accessory) DNA replicated separate from bacteria’s chromosome

cloning vector

DNA molecule that can carry foreign DNA into a host cell and multiply there

Restriction enzymes

Endonuclease that recognizes and cuts through DNA molecules foreign to bacterium, cutting at specific nucleotide sequences (restriction sites)

Restriction Sites

Also known as Palindromic sequences as they are the same forward and backwards

Restriction fragments

DNA segments that results from nucleases

sticky ends

single-stranded molecules exposed in a nuclease cutting