UNIT THREE CHP 4.pptx - Unit3Biology

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UNIT THREE

BIOLOGY

AREA OF STUDY #1: MOLECULES OF LIFE


EXAM REVISION LECTURE


CHP 4: MOLECULAR BIOLOGY IN MEDICINE

CHP 4 TOPIC 1:

HISTORY AND PURPOSE

Purpose of Molecular Biology


enhance knowledge of molecular biology


understand a range of applications of molecular biology in medicine, including


designer drugs, diagnosis of genetic conditions before and after birth, production
of hormones and plant vaccines.


Molecular Biology in Medicine involves


knowledge and manipulation of genetic material


design and development of drugs to prevent the specific action of an infective
micro
-
organism


design and development of drugs to inhibit the action of specific chemicals in the
body


manufacture of compounds for use by people deficient in a vital chemical, such as
a particular hormone


development and delivery methods for efficient drug use



Discovery of the link between inheritance and the human condition,
Aklaptonuria

(as an
inherited disease
) in 1902. Sir Archibald E.
Garrod

related this condition to a
lack of an enzyme



Oswald Avery: “inherited material was
DNA

in

1943



Watson & Crick


DNA structure discovery 1953



Today, the role of proteins, not just DNA is increasing in emphasis

CHP 4 TOPIC 1:

HISTORY AND PURPOSE

Example:
PKU


Phenylketonuria



Is an inherited disease


Prevelance

1 in 10 000


Affected person fails to produce the enzyme phenylalanine
hydroxyl
ase


Prior to 1960: untreated affected person unable to metabolise phenylalanine to
tyrosine


Build up of phenylalanine causes brain damage


Testing: today


mass spectrometry


Treatment:
supply of diet free of
phenylalanine


results in normal development

CHP 4 TOPIC 1:

HISTORY AND PURPOSE


Medical Treatments





Gene Therapy


Some genetic diseases can’t be treated by diet changes. Why not try to insert a
normal functional gene into cells that contain a defect. Such a procedure is called
gene therapy.




Defn
:
Gene Therapy


A medical procedure that modifies the genetic material of living cells of an individual so
that the
gentic

effect is corrected



Two categories of Gene Therapy

1.
in vivo gene therapy
given directly to a patient

2.
Ex vivo gene therapy
(cells manipulated outside the body then re
-
inserted)



Functional piece of DNA called a
cloned gene


often inserted with use of a
vector,
such as a virus:


Retroviruses


Adenoviruses

CHP 4 TOPIC 2:

MEDICAL TREATMENTS
USING MOLECULAR BIOLOGY


Topic CHP4.1 Questions:

1.
Which of the following are credited with discovering the structure of DNA: (circle)


Oswald Avery/ Sir Archibald E
Garrod
/ Watson & Crick

2.
The (base) cause of PKU is: (circle) nutritional/ genetic (
i.e

hereditary)/ environmental

3.
A series of linked metabolic reactions is called a: _____________ ________________



Topic CHP4.2 Questions:

1.
The manipulation of DNA to insert a preferred gen is known as: ____________________

2.
The two categories of Gene Therapy include: __________________, & _______________

3.
A functional piece of copied DNA is called: ______________DNA

4.
Two vectors used to insert (copied) DNA into an individual include: ___________ &
___________

5.
Which macromolecule is also used as a vector for the insertion of DNA into cells: _______



/8 Marks


Medical Diagnosis


Prenatal Testing

Genetic tests of
unborns

include:


Ultrasound


Chorionic
villus

sampling (CVS)


Amniocentesis


electrphoresis



Genetic Tests after birth include:


Presymptomatic

testing for; breast cancer & Huntington’s disease



CHP 4 TOPIC 3:

MEDICAL DIAGNOSIS
USING MOLECULAR BIOLOGY

Medical Diagnosis

Ultrasound:


Technique using sound waves to form an image of internal structures, including a
fetus

in its mothers uterus


Chorionic
villus

sampling (CVS)


Prenatal process of obtaining a sample of
chorion

tissue that surrounds a developing
embryo or early
fetus

and includes cells of embryonic or
fetal

origin


Amniocentesis


Procedure in which a sample of amniotic fluid that surrounds a
fetus

in uterus
(containing
fetal

cells) is obtained


Electrophoresis


Technique for sorting out lengths of DNA fragments through an electric field


Presymptomatic

Tests


DNA
-
based technique for distinguishing whether a person is ‘at risk’ but who shows no
clinical sign of a given genetic disease


CHP 4 TOPIC 3:

MEDICAL DIAGNOSIS
USING MOLECULAR BIOLOGY


Ultrasound:

Technique using sound waves to form
an image of internal structures,
including a fetus in its mothers uterus



Amniocentesis

Procedure in which a sample of amniotic
fluid that surrounds a
fetus

in uterus
(containing
fetal

cells) is obtained


Chorionic
villus

sampling (CVS)

Prenatal process of obtaining a sample of
chorion

tissue that surrounds a developing embryo or early
fetus

and includes cells of embryonic or
fetal

origin



Electrophoresis

Technique for sorting out lengths of DNA fragments through an electric field

Rational Drug Design


essentially involves finding out how the infective agent works against a cell
and using that information to design a drug that prevents the infective
agent from being able to do what it does


Example:
Relenza



anti influenza drug


Neuraminidase, protein on surface of the virus, allows exit of new virus
particles from a cell


Neuraminidase structure varies between virus strains


Scientists found a common structural component, which was the active site


Computer modelling of the active site was completed


A drug to bind with the active site was then designed



this technique, in which the active site of a molecule is determined and a
second molecule (the drug) is constructed to fit into the active site to inhibit
the activity of the first molecule, is called
rational drug design


CHP 4 TOPIC 4:

RATIONAL DRUG DESIGN

Insulin Production


role of insulin
: hormone that controls uptake of glucose


DNA sequence coding for insulin (a protein) production well known


Sequence of DNA can be constructed and inserted into a
plasmid vector


Plasmid inserted into bacteria where they replicate


Bacteria become insulin factories, secreting insulin


Insulin is isolated, purified and packaged into vials for diabetics

See figure 4.29
a&b



Growth Hormone Production


role of growth hormone:
growth


Normally produced by pituitary gland


Gene can be copied through genetic engineering


Factor VIII Production


role of Factor VIII:
involved in blood clotting (absence causes

haemophilia)


Gene on X chromosome (much more common in males as it is recessive)


Factor VIII produced by similar methods to insulin and growth hormone


CHP 4 TOPIC 5:
MANUFACTURING BIOLOGICAL MOLECULES


Topic CHP4.3 Questions:

1.
(Fill in the gaps)

2.
______________________ is a procedure in which a sample of amniotic fluid
(containing
fetal

cells) is obtained.

3.
______________________ is a prenatal process
wherby

a sample of the
chorion

tissue
surrounding a developing
fetus

is obtained

4.
The basis for ‘electrophoresis’ is that different versions of genes are of different lengths
and that DNA is ____________________ charged

5.
Presymptomatic

tests occur
before/ after
an at risk person shows signs of a disease


Topic CHP4.4 Questions:

1.
What is
rational drug design?


Topic CHP4.5 Questions:

1.
With insulin production, the DNA clone is inserted into what?___________

2.
What name is given to enzymes that ‘cut’ DNA: ________________

3.
What name is given to
ensymes

that ‘stick’ DNA together? ________________






Drug Delivery By Plants



The delivery of vaccines in plant material, as food, is currently being investigated. To develop
such vaccines:



the molecular structures of proteins in the infective agent that cause the immune response are determined



the DNA that codes for some of these proteins is introduced into the
plant genome



the plants are grown and harvested




Example: Japanese research team developed rice that can deliver a cholera vaccine by
genetically altering it to include DNA that codes for part of the protein of a cholera
bacterium (thus initiating an immune response!)


CHP 4 TOPIC 6:
DRUG DELIVERY


Drug Delivery By
Nanoparticles




are manufactured through
nanotechnology


1
-
100 nanometres in diameter, small enough to pass through a cell membrane


made of a double layer of phospholipids so that they mimic the plasma membrane


are used to deliver toxic drugs directly to target cells (such as tumour cells) reducing the
chance of affecting healthy cells


three compounds are attached to a
dendrimer

to be used in cancer treatment:


The drug
methotrexate

(to kill the cancer)


Five molecules of folic acid, a vitamin (attractive to cancer cells!)


A fluorescent stain (allows assessment and monitoring of the process)


CHP 4 TOPIC 6:
DRUG DELIVERY

Topic CHP4.6 Questions:

1.
List the three steps involved with ‘drug delivery by plants”


__________________________________________________________


__________________________________________________________


__________________________________________________________


2.
How many nanometres in: 1 mm______________ 1micron:______________

3.
Why are
nonparticles

for drug delivery encased in
phospholipid

bilayer
?
__________________________________________________________

4.
What is the name given to the
nanoparticle

used for drug delivery:___________________

5.
Why is folic acid added to the
nanoparticle

identified above?
___________________________________________________________________