DNA And The Book Of Life Flashcards
What did Gregor Mendel do
Formulated laws of heredity in 1860s
Austrian monk
Crossed plants and described offspring
What experiment did Mendel do
Crossed tall and short pea plants
Tall gene is dominant over short
What did Thoman Hunt Morgan claim
Genes lay on chromosomes
Worked with flies eye colour
Eye colour followed similar patterns to pea plant inheritence
Order of how things were discovered in molecular biology
1940 - relationship between genes and proteins
44 - genes made of DNA Oswald Avery
52 - DNa responsible for heredity in viruses
53 - watson and crick dna model
60 - proteins bind onto DNA that express genes
61 - mRNA discovered
61-65 - relationship of DNA to RNA to protein discovered link in DNA and protein sequence
What is. Gene
Hereditary unit of a living cell
Genetic code that codes for a mRNA
What is the central dogma
How info can pass from DNA sequences through RNA sequences to end up as protein sequences
What do structural proteins produce
Collagen
Elastin
What do signalling proteins produce
Insulin
Neurotransmitters
What di enzyme proteins produce
Amylase
Trypsin
What do transcription factors produce
Pancreatic duodenal homeobox protein
Signal transfucers and activators of transcription protein
How did archibald garrold know genes make proteins
Isolated a substance from joints of affected children
Enzymes responsible for build up of this substance (homogetistic acid)
What did garrod found out
Type of mould could have its DNA mutated by xray radiation
Many strains couldn’t grow unless extra nutrients were added
Many genes effect metbolism of specific amino acids required fro mould to grow
Gene expression regulation process
1) Rmodeling of chromatin (wrap tight or lose around histones)
2) Transcriptional control = whether genes switches on or off
3) Processing control
4) Transport control through nuclear pore
OR MRNA stability control
5) Translational control of protein synthesis
OR produces inactive mRNA
6) Protein degradation or Posttranslational control of protein activity
Positive and negative regulators
Positive = enhancers
Negtive = repressors
Combination of factors determines rate of transription
W2hat are the 3 criteria for DNA recoggnition by protein motif
Fits into major or minor groove
Has amino acids that can project into interior of double helix
Has amino acids that can bond with interior bases
How are genes switched on
Signalling molecules outside the cell bind to receptors that trigger cascades in the cell
OR
Nuclear receptors act as a receptor or DNA binding protein
WHat are mutations
Changes in nucleotide sequences of DNA that are passed on to the next generation
Two general types of mutation
Somatic mutations = somatic cells passed on by mitosis but not to sexually produced offspring
Germ line mutations = germ line cells that give rise to gametes, gamete passes on mutation in fertilisation
Whats a point mutation
Gain, loss or substitution of single nucleotide
Chromosomal mutations
Change position or cause DNA segment to be duplicated or lsot
What is phenylketouria disease
Phenylpyruvic acid builds up in urine
Mental retardation occurs
Dysfunctional enzyme which affected a single protein which caused the disease
How is a genetic disease caused
Mutant gene produces non functioning enzyme
Build up of substrate produced which causes disease
Treating genetic diseases
-Restrict substrate = Less substrate = less symptoms
-Add metabolic inhibitor = blocks harmful effects of built up substrae
-Restore missing enzyme = addition of wild type protein substitutes for the mutant enzyme
How are genetic diseases treated
Gene therapy = supply misisng genes by inserting a new gene that will be switched on in host cells
Challenges of gene therapy
Find appropriate vector
Ensure precise insertion into host DNA
Ensure appropriate expression
Select cells to target
What do ex vivo techniques do
Cell are removed from body
New genes inserted in lab
Cells returned to body so correct gene products are made
How does SCID use gene therapy (ex vivo)
IL2RG gene inserted into genome of SCID sufferer
Worked in many cases but leukaemia as consequence of treatment
Boy lived in bubble and died at 13 from viral infection from bone marrow transplant
What does in vivo gene therapt do
Gene inserted directly into body cells
Hope DNA will be incorporated into patients genome and disease will improve or disappear
Hierarchical sequencing
Overlap parts of sequences are aligned to create larger sequences
Larger fragments arranged in sequence produce chromosome map
Shotgun sequencing
Cuts DNA into smaller overlapping fragments that are sequences
Computers search for overlapping markers
Approach is faster and cheaper
What does pharmacogenomics do
Makes it possible to predict whether a drug will be effective
Aim is to personalise drug treatments
Nuclear transfer experiments process
Nucleus removed from unfertlised egg forming enucleated egg
Nucleud of embryo injected into enucleated egg
Eggs divide and develop into a clone from the original implanted nucleus
Cytoplasmic environment can modify cells fate
How does Pharming crops improve nutritional characteristics
Rice does not have beta carotene but has precursor molecule
Genes for enzymes that synthesize beta carotene from the precursor are taken from daffodils and inserted into rice
Pluripotent
Blastocyst embryonic stage
Retain the ability to form all of the cells in the body
Embryonic stem cells canbe removed from the blastocyst and grown in lab culture
