genetics

Molecular Genetics

DNA(deoxyribonucleic acid) - history, 1982-Griffith(suggested genetic info is being transferred, transforming principle), 1944-Avery(confirmed transforming principle),

1950-Chargaff( pairing rule of A=T and C=G), 1952-Hershey +Chase (confirmed DNA entered cells), 1953- Watson +Crick(Franklin)(double helix)

Structure- double helix, made of nucleotides that have phosphate group, deoxyribose sugar, Nitrogenous base (A,T: 2 bonds, C,G:3 bonds), backbone of a phosphate- sugar, runs in opposite directions 5'-3' and 3'-5'

Replication- this happens during interphase/synthesis, 1. Strand separation, dense in A,T. Bc its easier for helices to break. DNA gyrase relieves tension bf helices unwinds the DNA, helices breaks the H-bonds between the nitrogenous bases, ssBp's prevent the bases from coming back together. 2. Building complementary strands, primes makes an RNA(A,U,C,G) primer at 3', DNA polymerase 3 locates primer and Starts to build new strand 5'-3', DNA polymerase 1 removes primers and puts on correct DNA bases, DNA ligase joins Okazaki fragments on the logging strand

DNA REPLICATION

Extraction- isolating DNA from cells so it can be tested/studied. Genetic testing, forensic analysis, biotechnology research

CRISPR-gene editing tool that uses scissors to cut out parts of genes that need to be modified.

Central Dogma (Protein Synthesis) - Life existence, Takes DNA (Double, A, T,C,G, nucleus and undergoes transcription to make RNA(single, A,U,G,C, travels from nucleus to cytoplasm) then Translation to make a protein (amino acid)

Dna vs rna

DNA- deoxyribonucleic acid, deoxyribose sugar, double strand, A,T,C,G, stays in nucleus, stores genetic code, very stable

RNA- ribonucleic acid, ribose sugar, single strand, A,U,C,G, made in nucleus and works in cytoplasm, transfers code and helps make proteins, less stable can break down quickly

Both- are nucleic acids, have a sugar-phosphate backbone, contain nitrogen bases, store genetic info, are synthesized in the nucleus

Transcription: (nucleus) 1. Imitation, RNA polymerase attaches to the promotor region

(TATA box) and causes unwinding

1. Elongation, RNA polymerase moves along, DNA template strand in 3'-5' direction (no primer is needed)

2. Termination, when RNA polymerase hits the terminator sequence it breaks off and the mRNA Is free

Modifications- before mRNA can leave

1. 5' Cap, 7 G's are added, initial attachment site for ribosomes in translation. 2. Poly-A-Tail, 50-250 A's are added to 3' end, provides protection for digestive enzymes.

3. Splicing, uses splicesomes to cut out Introns(Non-coding) and connect Exons (coding)

Translation-making polypeptide from mRNA, 1. Initiation, mature mRNA enters cytoplasm, ribosomes bind to 5' cap. 2. Elongation, ribosome moves along mRNA in 5'-3' direction. New amino acids are added to polypeptide chain after reading

P-Site, first tRNA binds here with amino acid A-Site, binding site for tRNA

E-Site, tRNA with no amino acid leaves.

tRNA- transfer, charged and carrying amino acid at 3' end, uncharged means no amino acid, the anticodon recognizes the codon and brings correct amino acid

3. Termination, when stop codon (UAA,UAG,UGA) is read by ribosome complex, everything falls off

Woddle hypothesis- 3rd base may differ but it still codes for the same amino acid

Mutations- germ line- egg/sperm. Somatic- body cells

Spontaneous- errors in DNA replication, change in base letter (point)

Induced- caused by mutagenic agents (chemicals)

Point mutations substitution

Silent- no change in animo acid, no effect (wobble)

Missense- different amino acid, different polypeptide (sickle cell)

Nonsense- premature stop codon, lethal bc incomplete (cystic fibrosis)

Frameshift

Insertion/deletion- adding or removing base, shift in reading (Tay-sachs)

Chromosomal

Translocation- transfer of DNA fragment, not the same (Leukemia)

Inversion- DNA is flipped within chromosomes and reading backwards (miscarriages)

Transposable- gene jump with in a chromosome, introns.

Duplication- double gene fragments

Genetic Technologies-gel electrophoresis- separate DNA, RNA or proteins bases on size and charge using electric current. DNA samples are placed into wells in a gel, electric current is applied, negative DNA moves toward positive electrode, smaller fragments move through the gel, DNA bands are stained and can be seen and compared (DNA fingerprinting)

PCR-(polymerase chain reaction), make millions of copies of a specific DNA segment, DNA testing, genetic diagnosis, biotechnology

CRISPR- cut and edit specific areas of DNA, genetic scissors, RNA is programmed to match DNA, guides enzyme to spot.

Operons

Lac Lactose broken down by enzyme lactase

DNA3' Promoter Operator 3 genes that code for lactase 5'

The RNA polymerases binds to promoter to make mRNA, when the repressor binds to the operator it makes it so RNA poly. Can't transcribe, if there is lactose in the body and lactase needs to be produced lactose will bind to the repressor and change its shape to make it fall off and start the transcribing.

TBP-goal is to have enough tryptophan

DNA 3' Promoter Operator 5 genes to code for trp 5'

If there is no top the repressor can't fit on the operator because its changed shape, this makes top until there enough to stop. The top Corepressor binds to the repressor to make it fit on the operator and that shuts off coding.