Flashcards in TOPIC 4: GENETIC & EVOLUTIONARY INFLUENCES ON BEHAVIOUR Deck (84)
- Deoxyribonucleic acid (DNA)
- Double helix joined by nucleotides
- Nucleotides are
(A adenine)<=>(T thymine)
(G guanine)<=>(C cytosine)
- Made up of DNA segments
- Guide synthesis of proteins which form/alter physiologic systems, via RNA (ribonucleic acid)
- Structures in cell nucleus
- Comprised of 23,000 genes
- 23 pairs = 46 chromosomes
- 50% of chromosomes inherited from each parent, randomly selected.
Pair of genes occupying the same locus on a pair of chromosomes
Gregor Mendel (1865)
Cross bred peas to make hybrids
- Two original purebred strains, differing in one trait, one was round the other was wrinkled
F1 and F2 of Mendel's pea breeding
F1 : resulted in Rr(round) and Rr(round)
F2 : resulted in RR(round), Rr(round), Rr(round), rr(wrinkled)
- Can cause reduced head and brain size, motor coordination problems, intellectual disabilities and physiological disorders.
- effects 10 per 100,000
- caused by an enzyme that produces a enzyme that ineffectively metabolizes amino acid phenylalanine
- Allel is recessive
Where is phenylalanine found
found in some high protein foods, components of aspartame.
Environmental treatment for genetic defect (Phenylketonuria)
A trait cannot be accounted for by a single gene and is continuous rather than discrete.
The goal of epigenetics
The goal of epigenetics is to explain how the environment interacts with genetic information In the body.
why and how is protein translated.
Because almost every body cell has a copy of DNA, it has the capability of expressing a gene, by being transcribed into molecules of RNA, which are then translated into protein.
True or False - every gene in any cell is active
FALSE : Only 10-20% of genes are active in any cell.
What does Epigenetics guide?
They guide proper development of stem cells into different specialized cells of the body.
What is Epigenetics the study of?
Epigenetics is the study of changes in the regulation of gene activity and expression that are not dependent on gene DNA sequence.
Control of gene expression can occur in different ways
- DNA methylation
- Histone modifications
- Molecules called methyl groups attach to DNA
- This effects what gets translated into RNA and proteins, preventing gene expression.
- Methyl groups are present in foods, household chemicals, and environmental pollutants
- DNA is wrapped around protein structures called histones, like thread around a spool.
- some chemical groups attach directly to histones, loosing or tightening their connection to DNA, turning genes off or on.
How do experiences influence the epigenome ?
Certain antidepressants have been found to reverse both genetic and behavioural effects
How does genetic risk combine with experience and environment to produce identical twins?
- if one of the twins is autistic, there is a 60% the other is too.
- schizophrenia = 50%
- bipolar disorder = 75%
How do psychoactive drugs rewrite the epigenetic code?
- Addictions maybe cured--or even prevented-- by interrupting or reversing epigenetic changes. This can alter some genes temporarily, other more permanently.
Can epigenetic information be inherited?
Your experiences may actually cause changes In gene regulation that are passed on to your offspring.
- around world Galapagos visit and compared finches and adaptions
- compared present day creatures to fossil record
- wrote On the origin of species, which included evolutionary biology.
what were the 4 premises of On the origin of species.
1) life is dynamic: species change with time
2) evolution is gradual and continuous (sudden environmental changes ==> some species die out)
3) stats quo maintained in a static environment
4) all current organisms descended from an original ancestor
the 2 mechanisms
natural selection and artificial selection
selective breeding by nature
"survival of the fittest" : means suitability or match with the environment, not physical strength.
selective breeding by human action.
- individuals with desired traits encouraged by human action.
- pass on their genetics or characteristics.
how does genetic change occur
through two ways:
sexual reproduction and mutation