HHB Combined 1.2 - 1.3

DNA (deoxyribonucleic acid)

Molecule that holds the genetic code in living organisms.

Nucleotide

Component of DNA composed of a deoxyribose sugar, a phosphate and a base.

Deoxyribose

Found at 3' end of DNA strand. Its a sugar that is a component of DNA nucleotides.

Phosphate

Found at 5' end of strand. Component of nucleotide whcih forsm a strong bond with the sugar of next nucletotide to form the backbone of the molecule.

Base

Substance that is one of the 3 components of a DNA nucleotide and forms hydrogen bonds with another..

Sugar-phosphate backbone

Strong bonded between nucleotides on the same strand of DNA

Adenine (A)

DNA base that pairs with Thymine.

Thymine (T)

DNA base that pairs with Adenine.

Cytosine (C)

DNA base that pairs with Guanine.

Guanine (G)

DNA base that pairs with Cytosine.

Hydrogen bond

Weak chemical bond that links complimentary base pairs in DNA and therefor connects the 2 strands.

Antiparallel

Term used to describe the fact that DNA strands run in opposite directions

Double Helix

Shape of DNA molecule

DNA Polymerase

Enzyme in DNA replication that joins new nucleotides onto the 3' of the strand

Lagging strand

Strand that starts with a phosphate molecule and is made in fragments that then need to be joined together as it runs 5' to 3'

Leading strand

Strand that starts with a Deoxyribose sugar and is made continuously

Ligase

Enzyme that joins the fragments of the lagging strand together

Primer

Short strand of DNA nucleotides needed to begin DNA replication. Joins to 3' end of exposed strands

DNA Replication

Process of making 2 identical copies of the DNA molecule inside the nucleus of a cell

Template strand

The strand of DNA that is being copied into a complementary strand

PCR

Labratory method used to rapidly make multiple copies of a specific segment of DNA through repeated cycles of heating and cooling

Applications of PCR

amplifying DNA for paternity tests, diagnosing genetic disorders & for forensics to solve crimes,

Genome

An organism's entire genetic information, encoded in DNA.

Gene

Sequence of DNA bases that codes for a protein.

Chromosome

Structure made out of DNA and containing genes which forms prior to cell division. Each one has a homlogous partner. Mutations can happen to its structure.

Protein

Large molecule made when a polypeptide chain of amino acids folds into a specific 3D shape

RNA

Is a single stranded molecule containing uracil and ribose sugar. Has 3 different varieties.

mRNA

Single stranded nucleic acid which carries a complementary copy of the DNA code from the nucleus to a ribosome, has Uracil bases instead of Thymine

tRNA

Single stranded m molecule folded to expose anticodon, function is to carry a specific amino acid to a ribosome.

rRNA

Type of nucleic acid that makes up ribosomes along with protein

Peptide bond

Strong chemical bond linking amino acids in a polypeptide

Phenotype

Physical (outward) appearance of an organism, as a result of gene expression in combination with its environment.

Polypeptide

Chain-like molecule composed of several amino acids.

Codon

A sequence of 3 bases on mRNA that codes for a specific amino acid.

Ribose

5 carbon sugar present in RNA.

Exon

Coding sequence of mRNA which are joined together during RNA splicing

Intron

Non-coding sequence removed from primary transcript during splicing

Primary transcript

The strand of mRNA produced from transcription before RNA splicing takes place. consists of exons and introns

Ribosome

A structure in the cytoplasm, made of rRNA and protein, which is the site of protein synthesis (it joins amino acids togther with peptide bonds)

RNA polymerase

Enzyme responsible for the synthesis of mRNA primary transcripts from DNA.

RNA splicing

Joining of exons AND removal of introns from a primary transcript, to produce a mature transcript of mRNA.

Transcription

Copying DNA sequences to make a primary transcript (mRNA).

Translation

Production of a polypeptide at a ribosome, using the sequences of bases on mRNA.

Uracil

Base found in RNA, but absent in DNA, that is complementary to adenine (A).

Amino acid

Basic unit of a polypeptide chain.

Gene expression

A process which can be regulated (switched on/off), leads to production of a protein by transcription and translation.

Anti-codon

group of three bases on a tRNA molecule that are complementary to an mRNA codon. Function: ensure correct amino acid is added to polypeptide by ribosome