Genes Flashcards
What’s the function of the cell membrane
Controls what goes in and out of cell
Created compartment
Detects substances in environment
What is the function of the selectively permeable barrier
Permeability changed by cell
Provides fluidity (as molecules can move)
What’s cholesterol’s function in the cell membrane
Controls membrane fluidity
How does temperature affect cholesterol in the cell membrane
Greater fluidity at high temps lower at low temps
How does cystic fibrosis affect the alveoli
Partially blocked= reduced air flow into alveoli-> reduced conc. gradient= lower doffusion rate
Reduced airflow damage alveoli-> reduced king elasticity = lower diffusion rate
How does cystic fibrosis affect the lungs
Increased risk of lung infection- cilia can’t move mucus-> pathogens stay in lungs
How does cystic fibrosis affect the pancreas
Pancreatic duct blocked
Less enzymes in digestive system as they can’t leave
What is Cystic fibrosis caused by?
Mutation in the CFTR gene (Cl- channel)
What does this mutation mean
Na+ ion channel permanently open
Cl- ions can’t move into mucus from cell- no electrochemical gradient
What does this mutation result in
Na+ move into cell through open Na channel
Salt conc. in cell increases
Water moves (via osmosis) into cell from mucus making it extra sticky
What molecules are transported by diffusion
Small uncharged molecules eg: O2 , CO2
Lipid soluble molecules eg: vit A D E & K
What molecules are transported by facilitated diffusion
Small charges ions
Eg: Na+ & Cl-
How are molecules transported in facilitated diffusion
Chanel proteins- molecules travel through
Carrier proteins- change shape to move molecule
How are molecules transported in active transport
Via carrier proteins (protein pumps)
Uses energy from ATP to move molecules against conc. gradient
What do endo/exocytosis do
Move large quantities/ lather molecules
Active processes
Describe endocytisis
Molecules outside cell
Particles enclosed in a vesicle (made from cell membrane)
Vesicle brought into cell
Describe exocytosis
Vesicle inside of cell fuses with cell membrane allowing molecules inside to leave the cell
What do proteins make up
Insulin
Growth hormone
Tendons
Cartilage
Hair and nails
What are 3 proteins types in the cell membrane
Peripheral protein
Integral protein
Transmembrane protein
What are protein’s function in the cell membrane
Facilitated diffusion Enzymes
Receptors
What are glycolipids?
Polysaccharide attached to a lipid
What are glucolipid’s function in the cell membrane
Cell-to-cell recognition
Receptors
Antigens
What are glycoprotein’s function in the cell membrane
Cell to cell recognition
Receptors
Antigens
What is an amino acid made form
Carbon bonded to a H2N group
Hydrogen
Carboxylic acid group
R group (different side chains for different amino acids)
What’s the primary structure of proteins
Peptide bonds of amino acid sequence
What’s the secondary structure of proteins
2D arrangement of amino acid chain
Alpha helix or beta pleated sheet due to hydrogen bonds
What’s the tertiary structure of proteins
3D folding of secondary structure
Due to bonds between R groups
What’s the quaternary structure of proteins
3D arrangement of many polypeptide chains (not all proteins)
What type of bonds can form between r groups
Disulphide bridges
Ionic bonds
Van de Waals bonds (covalent)
What’s the structure of globular proteins
Compact spherical
Transports substances
Hormones, antibodies, enzymes
Soluble in water (form colloids)
Hydrophilic r groups outside
What’s the structure of fibrous proteins
Long tough parallel chains
Little tertiary/ quaternary structure
Insoluble
Structural roles
What is hydrophobic exclusion
nonpolar R groups exclude themselves from water by staying together (forms tertiary structure)
What is the lock and key model?
Enzymes are specific to the substrate they bind too.
What is the lock and key model?
Enzymes are specific to the substrate they bind too.
what is the induced fit model?
enzyme distorted
active site moulds around
substrate
What does enzyme concentration do to a reaction
more enzymes= faster reaction
more enzyme-substrate complexes formed
limited by substrate concentration
What does substrate concentration do to a reaction
more substrate= increased rate
more enzyme-substrate complexes formed
limited by enzyme concentration
What does temperature do to a reaction
increased temperature= faster rate
particles have greater KE
increased collision frequency
Too high= lower rate
Bonds between r groups break denaturing active site
What does pH do to a reaction
different enzymes work best in different pH values
H+/ OH- ions interact with R groups changing the shape
What is mono hybrid inheritance?
Inheritance of a characteristic controlled by a single gene
Define gene
Sequence of bases in a DNA molecule that codes for a sequence of amino acids in polypeptide chain
Define genotype
- alleles a person has
Define phenotype
- allele expressed
Define loci/locus
Location of a gene on a chromosome
Define homologous chromosomes
Equivalent chromosomes that have the same genes in the same loci (can have different alleles)
Define competitive inhibition
Molecules which bind to and block the active site (can’t form enzyme-substrate complex)
Define non-competitive inhibition
Molecules which bind to the enzyme changing the shape of active site (alters R group bonds)
Describe the structure of DNA
Phosphate group bonded to 5th carbon of a deoxyribose sugar bonded to an organic base
what’s a purine base
base with a 2 ring structure (adenine and guanine)
what’s a pyrimidine base
Base with 1 ring structure (thymine and cytosine)
What are the names of the bonds in a nucleotide
Phosphodiester (phosphate and sugar)
How is DNA packaged?
in proteins called histomes
These together form chromatin making chromosomes
What is DNA replication
the process of copying DNA when a cell prepares to divide
What’s the first step of DNA replication?
DNA helicase unwinds double helix
What’s the second step of DNA replication?
Free DNA nucleotides form hydrogen bonds with complimentary base pairs
What’s the third step of DNA replication?
DNA polymerase forms phosphodiester bonds between adjacent nucleotides in a condensation reaction
What’s the fourth step of DNA replication?
DNA ligase seals the 2 new strands
describe the DNA strands made by DNA replication
identical and semi-conservative
What experiment proved semi-conservative replication proven?
Changes isotope of nitrogen in the media during the second round of DNA replication from N15 to N14
What did the experiment show
both strands of DNA had a strand of both N14 &15 bases (N14 slightly lighter = higher band) after density-gradient centrifugation
2 strands of N14 DNA and 2 strands of N14/15 DNA when process repeated
What would be different if conservative replication was proven
after density-gradient centrifugation there would be 2 bands
1 lighter and 1 heavier
What would be different if dispersive/ fragmentart replication was proven
second density-gradient centrifugation would have 1 band of medium density (4 strands of N14/15 DNA)
What would be different if dispersive/ fragmentart replication was proven
second density-gradient centrifugation would have 1 band of medium density (4 strands of N14/15 DNA)
Define degenerate code
more than one triplet codes for the same amino acid
What’s the difference between DNA and RNA
RNA has 1 more oxygen atom in the sugar
Thymine replaced with Uracil
RNA is single stranded
What’s the first step of transcription
RNA polymerase attaches to promotor region of DNA breaking weak hydrogen bonds
What’s the second step of transcription
Complimentary RNA bases line up against DNA strand (exact copy) making mRNA
What’s the third step of transcription
RNA polymerase bonds nucleotides with phosphodiester bonds
What’s the fourth step of transcription
mRNA hits stop codon and disassociates from DNA
What’s the fifth step of transcription
mRNA leaves nucleus via nuclear pores
Describe the first step of translation
mRNA attaches to a ribosome
Describe the second step of translation
tRNA anticodons bind to complimentary mRNA codons forming hydrogen bonds
Third step of translation
ribosome facilitates the formation of peptide bonds of the amino acids (via condensation reaction) on complimentary anticodon
Fourth step of translation
tRNA leaves ribosome to be reused
Fifth step of translation
polypeptide chain folds forming a specific protein
define mutation
change in DNA sequence
what are the types of mutations
point mutations and frameshift mutations
what mutations are point mutations?
substitution (change of 1 base)
inversion (swaped order/ strand of bases)
what are frame shift mutations
insertions and deletions (addiding/ removing 1 base)
duplication (adding same base twice)
what are frame shift mutations
insertions and deletions (addiding/ removing 1 base)
duplication (adding same base twice)
when can mutations cause no change?
when the change is a degenerate of the original
