Gene Expressions

Gene

the basic functional unit of heredity

Proteins

(a polymer) are macromolecules composed of amino acids subunits (monomers)

polymer

molecules composed of many monomers; makes up macromolecules

monomers

small unit that can join together with other small units to form polymers

Polypeptides

are long linear chains of amino acids thata re covalently attached to kne another

Four level of Protein organisation

Primary, Secondary, Tertiary, Quarternary

Primary Structure

level of protein organization that pertains to the number & sequence of amino acids in a protein 's polypeptide chains

secondary structure

describes the shape of the protein. that are two type…

alpha helices and beta pleated sheets

are both considered to be protein secondary structures. And both are stabilized by hydrogen bond

Tertiary Structure

level of protein organization that pertains to the overall 3D shape of a protein.

Quarternary Structure

level of protein organization that pertains to th association of two or more polypeptide chains to form am entire protein

Functions of proteins

Oxygen transport, protein as enzymes, Antibodies as proteins, structural proteins, contractile proteins, signal proteins

Hemoglobin

iron-containing protein in red blood cells that carries oxygen for delivery to cells

Sickle cell anemia

a genetic disorder that causes abnormal hemoglobin, resulting in some red blood cells assuming an abnormal sickle shape

Hemoglobin S

Abnormal hemoglobin causing sickle cell disease.

antibodies

defensive protiens that have bonding sites whose 3D structure allows them to identify and bind to very specific foreign molecules

Epitope

the part of an antigen molecule to which an antibody attaches itself

Signal Proteins

kind of proteins such as hormone - insulin that carry extracellular signals from cell to cell and consist of two polypeptide chains linked together with disulfide bridges

Insulin receptor

a type of divergent tyrosine kinase receptor leading to many different signaling pathways in the cell

Two major structural classifications of Protein

Fibrous protiens & Globular Protiens

Fibrous Protiens

these proteins are insoluble in water & usually has structural, corrective & protective functions (e.g, keratins, collagen, myosins, elastins)

Globular Proteins

these are compact, generally rounded, and soluble in water proteins (e.g, egg albumin & serum albumin)

serum albumin

it plays a major role in transporting fatty acids

Simple diffusion

a process whereby a substance passes through a membrane without the aid of an intermediary such as an integral membrane protein.

facilitated transport

Passive transfer of a substance into or out of a cell along a concentration gradient by a process that requires a protein carrier.

Active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

Protein Synthesis

Process of creating proteins from amino acids.

Protein Synthesis (Eukaryotes)

transcription in the nucleus, RNA processing in the nucleus, translation in the cytoplasm along with Post translational

Translational stages

initiation, elongation, termination

Initiation (Translation)

brings together mRNA, a tRNA with the first amino acid, and the two ribosomal subunits

Elongation (Translational)

synthesis from start codon to stop codon

Termination (Translation)

The third, and final, phase of translation in which the ribosome reaches a stop codon on the mRNA; a release factor binds to the stop codon and the completed polypeptide is released

mRNA consists of

5' cap, 5' UTR region, coding region, 3' UTR region, poly (A) tail,

5' end of mRNA

start codon

3' end of mRNA

stop codom

tRNA consists of

anti codons, acceptor stem

Anti-codons

contains complimentary bases anti sequences

acceptor stem

portion of tRNA that is linked to an amino acid by aminoacyl-tRNA synthetase enzyme

Aminoacyl tRNA

is tRNA linked to its corresponding amino acid.

Piptidyl-tRNA

are tRNA that holds the growing polypeptide chains

rRNA has three bonding sites: (A, P & E)

Amino acyl, Peptidyl, Exit

Aminoacyle site

site in ribosomes where aminoacyl tRNA docks

Peptidyl site

P site in the ribosome

holds the tRNA that carries the growing polypeptde

it is also where the first amino acid (methionine) binds as it is starting the polypeptide chain

Exit (E) Site

is where the tRNA leaves the ribosomes

Transcription

(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA

Transcription phases

Initiation, Promoter escape, Elongation, Termination

Initiation (Transcription)

RNA polymerase attaches to the promoter region on the DNA and begins to unzip the DNA into two strands.

Promoter escape

Transition from initiation to elongation in transcription.

Elongation (Transcription)

RNA polymerase traverses the template strand and uses base pairing complementarity with the DNA template to create an RNA copy

termination of transcription

RNA polymerase reaches a terminator sequence (Stop codon) and detaches from the template

Capping

a protective cover on one end

Polydenylation

a long tail a protection

Splicing

the process of removing introns and reconnecting exons in a pre-mRNA

translation

Process of synthesizing proteins from mRNA.

Translation four phases

Activation, Initiation, Elongation, Termination

activation (translation)

tRNA must be loaded with an amino acid

Initiation (Translation)

mRNA, first tRNA and ribosomal subunits assemble

Elongation (Translation)

begins by the appropriate aminoacyl-tRNA binding to the codon in the A site of the ribosome.

Termination (translation)

the A site of the ribosome facses a stop codom

Post Translational Events

enzymatic processing of a polypeptide chain following translation & peptide bond formation

Protein folding

the process by which a protein structure assumes its functional shape or conformation and secondary & tertiary structure

Enzymes

are biological catalyst that help speed up chemical reactions in our bodies

Catalyst

substance that speeds up the rate of a chemical reaction

Digestive enzymes examples

Carbohydrase, lipase, protease

carbohydrase

An enzyme that breaks down large carbohydrate molecules into simple sugars.

lipase

enzyme that breaks down fat

Protease

An enzyme that breaks down proteins into amino acids.

Types of enzymes

Intracellular enzymes and extracellular enzymes

Intracellular Enzymes

Enzymes that function within cells

Extracellular enzymes

enzymes that act outside of the cell in which they are produced

Properties of enzymes

it generally work very rapidly, can be used again but not forever, can work in either direction, affected by temperature, assign to specific reactions

substrate

the substance acted upon by an enzyme

product

A substance produced in a chemical reaction

denatured

loss of an enzyme's normal shape so that it no longer functions; caused by a less than optimal pH and temperature