Ch. 9 Bio SD Mesa

Indels

insertions and deletions

Insertions

additions to nucleotide pairs in a gene

Deletions

losses of nucleotide pairs in a gene

Antiparallel

In a DNA double helix, the two backbones run in opposite 5’ —> 3’ directions. An arrangement known as:

Gene

• unit of inheritance

• region of specific nucleotide sequence in a chromosome

• DNA sequence that codes for specific polypeptide chain

Watson and Crick

Who introduced an elegant double-helical model for the structure of DNA?

Rosalind Franklin

Who produced a picture of a DNA using x-ray?

DNA polymerase

enzyme that catalyzes the synthesis of new DNA at a replication fork

Semiconservative Model of DNA

When DNA is replicated, it will contain one “old” strand and one “new” strand

Nucleotide-pair substitution

replaces one nucleotide and its partner with another pair of nucleotides

Silent mutations

have no effect on amino acids encoded by a codon because of redundancy in the genetic code

Missense mutations

code for an incorrect amino acid

Nonsense mutations

change an amino acid codon into a stop codon, nearly always leading to a non-functional protein

Frameshift mutation

Alteration of the reading frame by insertion or deletion of nucleotides

Sickle Cell Mutation

Example of a missense mutation

Cas9

enzyme found in bacteria originally intended to remove viral DNA from cells; now used to genetically modify organisms

Genotype

complete set of genetic material

Phenotype

observable physical or physiological expression of the genotype

RNA processing

adds a cap and tail, removes introns, and splices exons together before leaving the nucleus

DNA ligase

the enzyme that catalyzes the joining of DNA fragments together

helicase

an enzyme that helps to open up the DNA helix during DNA replication by breaking the hydrogen bonds

lagging strand

The strand that is replicated in short fragments and away from the replication fork

leading strand

The strand that is synthesized continuously in the 5' to 3' direction; same direction as the replication fork

replication fork

the Y-shaped structure formed during the initiation of replication

Transcription

Conversion of DNA into RNA

Translation

Conversion of RNA into proteins

Mutation

any change in the nucleotide sequence of DNA

Common Mutagens (cause mutations)

X-ray, UV, Chemicals (Benzene and Formaldehyde), Radon Gas

Viruses

• between living and non-living

• protein coat on outside

• genetic material inside

• extracellular form

• need a host to reproduce

Lytic Cycle

Virus cycle in which a virus overtakes a host cell, forces it to produce more viruses, and then lyses to spread the virus

Lysogenic cycle

Virus cycle in which a virus integrates its genetic material with the host cell’s DNA, and will lie dormant as the cell replicates until triggered.

Enveloped Virus

A kind of virus encased in a membrane layer which it takes from its host cell upon exiting, allowing it to “hide” from the immune system for longer

Flu

An enveloped virus that has 8 different segments, which can recombine in different hosts (avian, porcine, or human), creating new strains frequently.

Codon

three nucleotides in mRNA that specify the addition of a particular amino acid

double-stranded circular; double-stranded linear

Prokaryotes contain a ________chromosome, and eukaryotes contain ________ chromosomes.

DNA polymerase proofreading

The initial mechanism for repairing nucleotide errors in DNA is ________.

Promoter

a specific sequence of DNA nucleotides

Nucleolus

The RNA components of ribosomes are synthesized in the ________.

epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels

Control of gene expression in eukaryotic cells occurs at which level(s)?