Gene Expression
Below is a major website complete with interactives and information as a start point for this topic. it covers the basics and then goes into very good depth. You should keep this as one of your prime sites to visit for help.
DNA STRUCTURE
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This next clip is an explanation of how DNA makes copies of itself, ready for cell division. This is part of the Cell processes standard, but we have it here, because it leads into making proteins.
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Understanding the leading/lagging strand ideas
The clip beside is a bit of revision on the nucleic acids in general if you need to refresh your memory!!
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PROTEIN SYNTHESIS
HOW THE CELL MAKES PROTEINS
Wide reading: An explanation of the need for proteins and their role in cells:
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This is a "protein" made using information on the codons to add a particular 'amino acid" (fluffy thing!) to a protein chain. Each fluffy represented a specific amino acid and was coded for by a triplet codon.
Mutations
These are changes in the DNA. The sequence of the bases is changed and this can result in an overall change in the appearance of an organism.
Mutations are caused by a change in DNA sequences (Bases) or an alteration in whole chromosomes
The change results in the wrong amino acid(s) being in the final polypeptide chain. This can alter how the protein functions and can completely change aspects of the whole organism. If the polypeptide is an enzyme it can mean the proper cell reactions do not occur.
Some are harmful or lethal.
Some are useful.
Mutations are only inherited if they are in the gametes. (egg & sperm). They are not inherited if they are in the body cells (Somatic cell)
Mutations are the ONLY source of variation or genetic diversity and are the “raw material” for evolution
TYPES OF MUTATIONS
2 main kinds:
Mutations are caused by a change in DNA sequences (Bases) or an alteration in whole chromosomes
The change results in the wrong amino acid(s) being in the final polypeptide chain. This can alter how the protein functions and can completely change aspects of the whole organism. If the polypeptide is an enzyme it can mean the proper cell reactions do not occur.
Some are harmful or lethal.
Some are useful.
Mutations are only inherited if they are in the gametes. (egg & sperm). They are not inherited if they are in the body cells (Somatic cell)
Mutations are the ONLY source of variation or genetic diversity and are the “raw material” for evolution
TYPES OF MUTATIONS
2 main kinds:
- Point mutation: effects a single base
- Block mutations: effect large sections of DNA or sometimes whole chromosomes. (Can happen in crossing over.)
- Substitution
- Deletion
- Insertion
- Inversion
- Duplication
This is a 7 min clip from the Amoeba sisters which explains the basics of mutation for you:
Mutagens
Some mutations happen at random - these are called spontaneous mutations
Mutagens are anything that can cause a mutation.
Radiation
X-Rays
Pesticides
Carcinogens (cause cancers)
Most mutagens also cause cancers as they alter the functioning of the cell replication processes
METABOLIC PATHWAYS
The Effect of the Environment
Epigenics
The way genes end up actually being expressed often depends on the environment. So the phenotype is a result of both the genes/alleles and how they interact with the environment.
More and more we are finding out that the environment (way we live, what we eat etc) has an effect on our genes. This is a new emerging science and is called "Epigenics"
More and more we are finding out that the environment (way we live, what we eat etc) has an effect on our genes. This is a new emerging science and is called "Epigenics"
This is a link to Utah university site on "Epigenics". There are some very clear examples and some great interactives for you to do
Twin studies give scientists some great examples to investigate how bringing up twins in different environments can effect their phenotype.
A quick 3 min Ted talk for extension into this topic. Dean Ornish on genes and their expression. It is quite fast paced.
The link below is to an advanced reading on Epigenetics: How the food we eat can effect the expression of different genes.