Gene Technology Overview

Gene technology aims to create bacteria that produce human proteins by combining human and bacterial genes.

1. Isolate the human gene e.g the gene for insulin
2. Cut open a vector and insert the gene into it
3. Put the vector back into fast-growing bacterial cells
4. Identify the cells that have taken up the human gene
5. Grow these using an industrial fermenter
6. Isolate and purify the human protein made by these cells

The Cell Cycle

G1: Cells prepare for DNA replication
S: DNA replication occurs
G2: The cell grows more until mitosis
M: Mitosis occurs (P, M, A & T)

Mitosis

Mitosis:

• Cell division to produce new cells from old


• Two daughter cells identical to the parent cell
  
  

Prophase -

1. The chromosomes coil, becomming shorter and fatter


2. The nuclear envelope disappears


3. Spindle fibres are formed

Metaphase

1. Chromosomes line up along the equator


2. Spindle fibres attach to centromeres

Anaphase

1. Centromeres divide


2. Spindle fibres contract and pull sister chromatids to opposite ends of the cell


3. The chromosomes are now called chromosomes again

Telophase

1. The two groups of chromosomes form at opposite ends of the cell


2. Nuclear envelopes form around each group


3. Chromosomes uncoil to become long and thin


4. Cytokinesis takes place so that two new cells are formed

Interphase

1. The new cells form more cytoplasm and carry out normal functions


2. DNA replicates.

Translation

This is the process that converts mRNA into functional proteins.

1. The mRNA molecule moves into the cytoplasm and attaches itself to a ribosome at its' 'start' codon.
2. The ribosome moves along the mRNA strand, 3 bases at a time.
3. As this happens, tRNA molecules base pair with the mRNA strand. These carry with them amino acids.
4. Adjacent amino acids will then bond, forming a protein.
5. The remaining tRNA and mRNA molecules will then split

Terms and Definitions

• Degenerative Code - This means that some amino acids are coded for by more than one codon
• Non-overlapping - Specific 'start' codons ensure that ribosomes 'read' the mRNA in the correct way.
• Introns - Reigons of non-coding DNA, removed from mRNA before translation
• Semi-conservative replication - When only half/one strand of the DNA is replicated. This produces exact copies of the origional DNA.
• Gene - A length of DNA that codes for a single protein.

Introns and Exons

Intron - Reigons of non-coding DNA. They are copied onto the nRNA during transcription then removed before they are used to code for proteins in the ribosome.

Exon - The coding reigon of DNA.

Transcription

This is the process that produces a molecule of mRNA from DNA.

1. The DNA helix unwinds as the hydrogen bonds between the base pairs break.
2. Free DNA nucleotides in the nucleus, pair with the exposed DNA bases on the sense strand.
3. These are held together using the enzyme DNA polymerase
4. This new strand of DNA nucleotides (mRNA) then separates from the sense strand and leaves the nucleus.