Wk 2: comm & genetics Flashcards
Codominance
- Two alleles are dominant over a recessive allele
- When both dominant alleles present, both phenotypes are expressed
Example human ABO blood groups
Mutation is lethal
when desired protein product is not produced
- Cannot perform correct function
Mutation is unlethal
stays in population as new allele
Possible loss or gain of 1+ nucleotides
- Change in** reading frame **of gene: protein cannot function
- Wrong protein produced and early stop codon
Mutations
- Change in DNA sequence of a gene: new allele
- Single or multiple nucleotide change/swap
Outcomes of Mutations
- Functional protein produced (no change)
- Protein produced doesn’t work as well
- Protein cannot function or produce insufficient amount
Hormone roles in regulating
Contraction of smooth and cardiac muscle cells
Glandular secretions
Immune system response
Control growth and development
Regulation of reproductive systems
Target cell response to a hormone is based on
The hormone’s concentration in the blood
The number of hormone receptors on the target cell
Synergistic
enhance action of another hormone
Eg) glucagon and adrenaline: both raise blood glucose
Antagonistic
oppose action of another hormone
Eg) glucagon raises blood glucose; insulin reduces it
Hormones are secreted in short bursts when needed. Secretion is regulated by
Signals from the nervous system
Chemical changes in the blood/cells
Other hormones
Water soluble hormones
can travel into a watery liquid
Type of hormone: amine, peptides (insulin/glucagon)
Lipid soluble hormone
can travel through structure such as membrane
Type of hormone: steroid and thyroid
Ligand Receptors
specific proteins that function when a specific molecule binds to the receptors
When ligand binds
the receptor can change conformation
Ligand binding can cause
Metabotropic: transmitting a signal into the cell
Ionotropic: open a channel for molecules to go through
DNA
double stranded helix and has 4 bases
Coiled into histones and placed in chromosome
Chromosome = a long DNA molecule
Bases: complementary pairing
- Adenosine and thymine
- Guanine and cytosine
DNA and nucleotide sections
- Phosphate group
- Deoxyribose sugar
- Nitrogen-containing base
- Nucleotide pairs joined by hydrogen bonds
Gene
unit of heredity
- specific location on chromosome
- codes for a specific protein or enzyme to be made
Allele
specific DNA sequence at a gene locus
- Homozygous: identical alleles
- Heterozygous: different alleles
Genotype
the two alleles an individual has at a gene locus (genetic makeup BB, Bb)
Phenotype
the observable expression of the two alleles
(can be effected by interaction with the environment)
Sex-chromosome
- chromosome pair 23
- XX (females) and XY (males)
Cell division
- Process by which cells reproduce themselves
Mitosis
replaces somatic/body cells
cell produces two identical copies of it
Meiosis
forms gametes in ovaries and testes
Prophase
Chromosomes condense & become visible
Spindle fibres emerge from centrosomes
Nuclear envelope breaks down
Centronomes move towards opposite poles
Prometaphase
Chromosomes condense
Kinetochores appear on centromeres
Mitotic spindle microtubules attatch to kinechores
Metaphase
Chromosomes line up at metaphase plate
Each sister chromatid is attached to a spindle fibre originating from opposite poles
Anaphase
Centromeres split in two
Sister chromatids pulled to opposite poles
Spindle fibres elongate cell
Telophase
Chromosomes arrive at opposite poles and de condense
Nuclear envolope material surrounds each set of chromosomes
Mitotic spindle breaks down
Spindle fibres push poles apart
Cytokinesis
Animal cell: cleavage furrow seperates daughter cells
Plant cell: cell plate seperates
