Biology Module 5

Deoxyribonucleic acid (DNA)

• is a nucleic acid composed of two strands of polynucleotides twisted to form a double helix

• stores genetic info

• deoxyribose sugar

• thymine as base

• stable

Ribonucleic acid (RNA)

• a polymer of nucleotides

• single stranded

• ribose as sugar

• uses uracil as base

• phosphate + uracil + ribose = RNA

• less stable than DNA

Rosalind Franklin

• photographed DNA for the first time.

  • able to see DNAs double helix structure

Nucleotides

• the basic building block of DNA and RNA

• sugar combines with a phosphate group and a base compound to form a ______. 

• Each nucleotide is composed of:

  • A sugar (deoxyribose), A phosphate group , And one of four bases

    • Adenine (A), Cytosine (C), Guanine (G), or Thymine (T)

    • Phosphate + deoxyribose = nucleotide

DNA Replication

• the duplication of a DNA molecule

• Occurs in S phase of the cell cycle

• occurs rapidly when an embryo is developing, when a cell becomes cancerous or when a virus hijacks a cell

Polymerase Chain Reaction(PCR)

• Artificial DNA Replication

• A laboratory technique

• Can produce millions of copies of a targeted DNA sequence in just a few hours

• heat → primers pair w/ DNA → produces new copies of DNA

Restriction Enzymes

• DNA is cut into fragments using ____ _____. 

  • unique to a specific person

Gel Electrophoresis

• separates DNA fragments on basis of their sizes

• Allows for comparison to other DNA that has been cut with the same restriction enzymes

Identical Twins

• result from a fertilized egg splitting

• genetically identical

• shared placenta 

Fraternal Twins

• result from two eggs being released at the same time

• separate placentas

Transcription

• the process of creating an RNA copy from a DNA sequence

  • similar to copying a document from one format to another

Translation

• ribosomes convert the genetic information in mRNA into proteins

• making proteins based on the instructions provided by the mRNA

Genetic Code

• the rulebook that cells use to translate DNA (or RNA) into the building blocks of proteins, called amino acids

Codon

• sets of 3 nucleotides that tell the ribosomes which amino acid to add

  • codes for only ONE specific amino acid

• 2 types→ start + stop

Start Codon

• AUG

• a three-nucleotide sequence (a codon) in messenger RNA (mRNA) that signals the beginning of protein synthesis (translation)

Stop Codon

• UAA, UAG, UGA

• do not code for an amino acid

• translations stops when these codons are reached

Envelope Protein

• used to disguise the virus and allows the virus to attach to host cells

• This is what is used to make vaccines

• spikes used to attatch + disguise viruses

Viral Envelope

• is a phospholipid bilayer

Phenotypic Plasticity

• change in gene expression due to environmental influences.

  • skin tan

Noncoding DNA

• is DNA that does not code for any kind of functional RNA

  • 95% of genes don’t code for anything important

Introns

• noncoding sections interspersed with the coding regions of a gene or exons

Exons

• code for protein

• a segment of a DNA or RNA molecule that contains the instructions for building a protein

• Introns are cut out and the ____ are pieced back together to make mRNA

Retroviruses

• a type of virus that uses RNA as its genetic material instead of DNA

• work retroactively

• uses a special enzyme called reverse transcriptase to convert its RNA into DNA

Reverse transcriptase

• used by retroviruses, a ribosome like structure

• an enzyme, found in retroviruses like HIV, that creates a DNA copy from an RNA template

Integrase

• an enzyme that helps a virus insert its own genetic material (DNA) into the DNA of the host cell it has infected

Frameshift mutation

• alter the protein so extensively that they invariably destroy the normal function of the protein and produce a severe phenotype

Silent mutation

• causes no change in the structure of the protein, and therefore no change in the phenotype of the organism

Adenine

• a base that always pairs with Thymine (T)

Cytosine

• a base that always pairs with Guanine(G)

Guanine

• a base that pairs with Cytosine

Thymine

• a base that always pairs with adenine(a)

uracil

• a key base of RNA

gene expression

• RNA helps to regulate this

• the manifestation of the information encoded in a gene as a specific phenotype

prion

• proteins that fold other proteins incorrectly

• ______ diseases, like mad cow disease, are the results of folding proteins folding incorrectly, resulting in a protein that does not function properly.

nucleocapsid

• protects DNA/RNA

protein folding

• strand of amino acids made into its functional shape