HUMAN BIOLOGY NOTES

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23 Οκτ 2013 (πριν από 4 χρόνια και 16 μέρες)

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HUMAN BIOLOGY NOTES

Biotechnology (Chapter 21
):

Biotechnology:
is using organisms to manufacture useful products.

Gene cloning:

The process of making large quantities of desired piece of DNA once
it has be isolated.

Genome:
Is the complete set of genetic information of an organism.

Hereditary disease:

caused by defective genetic information being transmitted
from parents to their children.

Mutations:

A change in a gene or chromosome leading to new characteristics in an
organ
ism.

Nucleotide:
The basic structural unit of a nucleic acid that consists of a simple
sugar, a phosphate group and a nitrogen base.

DNA profiling:

Can be created from a very tiny sample of DNA (e.g Saliva or
fingerprint). From a single sample many copies

can be produced using PCR. Can be
used for establishing an individual’s identity, anthropological research, detecting
genetic mutations or genetically inherited diseases early.

DNA sequencing:
Is the determination of the precise order of nucleotides in a
sample of DNA. By comparing DNA sequences, changed alleles can be detected and
will show whether an individual has a particular disease. It enables sequences to be
easily compared.



Process steps:

1)

A single stranded piece of DNA is amplified many times
using the polymerase
chain reaction.

2)

The segment of the DNA is cut at specific points using special fluorescent
primers.

3)

The replicated DNA fragments, differing in size by a single base, are the
separated using gel electrophoresis.

4)

Comparing DNA sequences

can be used to detect changes in alleles, or
whether a person has a particular disease (sickle cell anaemia, cystic
fibrosis).

Gel electrophoresis:
Process in which DNA fragments can be sorted into different
sizes using an electric current.



Process step
s:

1)

Cut DNA fragments into smaller pieces using
restriction enzymes

(are
enzymes from bacteria which are used as “chemical scissors” to cut strands
of DNA into pieces. Restriction enzymes cut DNA at specific sites called
recognition sites
.)

2)

Fragments are st
ained in fluorescent dye.

3)

Solution is placed into small wells in the gel plate.

4)

Plate is placed in the electrophoresis cell.

5)

DNA is negatively charged so will move to the end of the cell where it is
positively charged.

6)

Larger fragments will move slower tha
n smaller fragments.

7)

Different sized fragments are seen as bands across the gel.

^^ This can be used for DNA profiling or DNA fingerprinting. Using this
technique, person that carries a gene that causes a hereditary disease can be
identified. DNA profiling enables many genetically inherited diseases to be
detected at an early age.

Pol
ymerase Chain reaction (compounding amplification of original molecule has
caused a chain reaction):
It is like a biological photocopier. It is used for creating
multiple copies of a specific section of DNA from a sample (DNA amplification).



Process ste
ps:

Denaturing, hybridization, and synthesis.

1)

Denaturing
-
involves heating the template DNA at 95 degrees to separate
the two strands.

2)

Hybridisation
-

Mixture is cooled to 50
-
60 degrees, allowing two single
-
stranded primers to bind to their complementary DNA

sequences in the
template DNA.The primers act as starting points for DNA replication.

3)

Synthesis
-

Mixture is heated to 72 degrees and the

DNA polymerase
moves along the two template strands of DNA. The region between the two
primers is synthesized. DNA syn
thesis is stopped by heating to 95 degrees
again, which separates strands so that replication of the DNA can begin
again. Each cycle takes 3
-
5 minutes.

DNA polymerase:

An enzyme that attaches nucleotides to a DNA strand during
DNA replication.

Genetic pr
obe:

is a fragment of DNA or RNA labelled with radioactive isotopes or
a fluorescent marker that is used to detect the presence of a specific sequence of
bases in another DNA or RNA molecule. Used to detect the presence of the allele
responsible for heredi
tary diseases such as cystic fibrosis.

Recombinant DNA technology:
deliberate manipulation of DNA.

Recombinant DNA:

Synthetic DNA; made using genetic engineering techniques in
which genes from one source are inserted into a DNA molecule from a different
s
ource.

Uses include production of insulin, vaccines,
and gene

therapy.








Definitions for recombinant DNA technology:

Blunt ends:

The ends produced by a straight cut of a sequence of nucleotide bases

Ligase:
An enzyme capable of combining two small
single
-
strand DNA into one
single structure.

Phage:

Virus that infects bacteria.

Plasmids:
Small circular strands of DNA. Composed of only a few genes and are
able to replicate independently within cells.

Restriction enzyme:
Enzymes that cut strands of DN
A at specific sequences of
nucleotides.

Staggered cut:

Produced when a restriction enzyme creates fragments of DNA
with unpaired nucleotides that overha
ng at the break in the strands; called sticky
ends.

Straight cut:

Produced when a restriction enzyme mak
es a clean break across the
two strands of DNA so that the ends terminate in a base pair; called blunt ends.

Sticky ends:

The overh
anging ends produced by a staggered cut of a sequence of
nucleotide bases.

Vector:

Bacterial plasmids, viral phages or other
such agent used to transfer
genetic material from one cell to another.

Process for Human Insulin Production:


Gene therapy:

aims to treat or cure genetic abnormalities by replacing faulty
genes with healthy ones.