DNA (U3) Flashcards
Nucleic Acids
2 types - DNA and RNA (Both polymers of nucleotides)
DNA Structure
Double Helix made up of repeating nucleotide units
Nucleotides
Made up of 3 main parts
Phosphate (phosphoric Acid); 5 carbon sugars (deoxyribosome); One of four nitrogen bases
4 nitrogen bases
Adenine and Guanine (Two-carbon ring bases; purines) Thymine and Cytosine (One-carbon ring bases; pyrimidines)
A+T and G+C
DNA Replication
- Untwisted by enzymes (helicase) breaking the bonds
-New complementary nucleotides pair with complementary bases on the exposed strand (ligase glues sugar-phosphate backbone together)
-Winds back up into helix shape
(Called semiconservative)
DNA functions
Replicates itself (each new cell as identical copy)
Controls activities by producing proteins
Undergo occasional mutations
recombinant DNA
DNA genes from 2 different organisms
Uses for recombinant DNA
- generate DNA library
- Identify Specific genes
- Produce synthetic copies of genes to mass produce chemicals like insulin
- Insert genetic material into chromosomes that will regulate functions
RNA
Sugar = Ribose; Bases = AUCG; Single-Stranded; protein synthesis; Found in nucleus and cytoplasm
Protein Synthesis
Uses DNA to create protein - DNA contains instructions to create proteins; Proteins affect our characteristics
Protein is created in cytoplasm from mRNA strand
Transcription
process of making mRNA from DNA template
Hydrogen bonds between base pairs are broken to provide DNA template (Polymerase)
free-floating nucleotides join selected genes on DNA template (polymerase assist)
(Ligase) glues sugar-phosphate backbone back together; enzymes break the new hydrogen bonds, RNA strand formed
Translation
process to go from mRNA to protein
Initation - mRNA associated with ribosome in cytoplasm; larger subunit attaches to mRNA; first tRNA arrives with anticodon and binds to complimentary mRNA forming functional complex
Elongation - second tRNA peptide bonds with second codon; ribosome moves down mRNA by 1 codon; third tRNA bonds with 3rd codon…
Termination - Elongation continues until termination (stop) codon reached; finished protein released; mRNA read by more ribosomes or disenigrates
Codons
every 3 bases in DNA strand code for 1 amino Acid; once code is transcribed each set of three on mRNA is called a codon (64 possible combinations)
AUG = start codon; UUA and UAG = stop codon
at very end always a adenine tail to show mRNA is still functional, falls off after used
Gene Mutation
permanent aleration in DNA sequence
Hereditary Mutations/Germline mutations - in gametes
Aquired/Somatic mutations - occur as sometime in persons life, only in certain cells - body cells
Chromosomal mutations
Deletion - Peices breaks off (lost); Duplication; Inversion - piece breaks off and reattches reversed; Translocation - piece breaks off attaches to nonhomologous chromosomes; Nondisjunction - pair of chromosomes fail to separate during cell division; Point Mutations - change in single nitrogen base; Frame shift mutation - addition/deletion of nitrogen base
Environmental Mutagens
Chemical (drugs, fertilizers, food additives) and Radiation
Examples
Cancer (somatic mutation); Down Syndrome (chromosomal translocation); Sickle Cell Anemia; Hemophelia (germ cell mutation
Metabolism
Refers to all chemical reactions of a cell
Enzymes; Apoenzyme; Coenzyme
A protein Catalyst (speeds up certain reactions)
(protein portion)
(non-protein portion)
Speeds up reactions by lowering activation energy
Substrate; Activation energy
reactant enzyme acts on
many reactions won’t occur unless energy is added to start reaction off
Thyroxin; Thyrogolbulin
-Protein hormone secreted into blood stream by thyroid cells
Stimulate most cells to metabolize faster
-storage form of thyroxin
Simple goiter; exothalmic goiter
- thyroid gland unable to meet demands of body; enlarges to compensate
- Graves disease - excessive production of thyroid hormome
Lock and Key theory
Reactants must be brought close together; bond to active site on enzyme (enzyme sometimes changes shape for reactants); reaction occurs and products are released (enzyme goes back to tertiary shape
(enzyme acts like key unlocking substrate activity)
Metabolic Pathway
Begining subtrate - intermediate products/reactants - final product
1 enzyme 2 enzymes 3 enzymes
Factors Affecting Enzyme Activity
HEAVY METALS - Bond with parts of enzyme changing their shape (noncompetitive inhibition); COMPETITIVE INHIBITION - molecules shaped like substrate competing with them; TEMPERATURE - Cold temperature slows down enzymatic reactions (high temps cause them to stop); PH - operates best at preferred ph level; SUBSTRATE CONCENTRATION - there greater the concentration, the greater the rate of reaction; ENZYME CONCENTRATION - more enzyme, greater rate of reaction
