biology paper 1

Created by

nora s

Cards (25)

what is a gene? 
a small section of dna that codes for a protein
what does a gene do?
codes for a sequence of amino acids
what happens when amino acids combine?
they form a protein
how many types of amino acids are there?
twenty
what is a genome?
a genome is the entire set of genetic material in an organism
what is a chromosome?
A chromosome is a thread-like structure made of DNA and proteins that carries genetic information in the form of genes.
what is an allele? 
different versions of the same gene
how does alleles work for humans?
humans have two alleles one from each parent which can either be heterozygous or homozygous
how does the phosphate matching the sugars work?
the phosphate of one nucleotide bonds to the sugar of the next nucleotide and the process keeps repeating until it forms a long chain
bases stick out the side to hold strands together
only complementary bases can pair to each other
steps of transcription
rna polymerase binds to the non coding region
dna strand unzips
rna polymerase moves along one strand
base pairing between dna and rna make a complementary MRna strand
transcription stops when RNA polymerase reaches termination sequence on DNA
steps of translation
trna brings amino acids into the ribosomes
anticodons in trna are complementary to codons
meaning amino acids are joined in the correct order
the ribosome joins the amino acids in order to form a polypeptide
how to genetic engineering can be for insulin
isolate insulin gene using restriction enzyme to form sticky ends
2. use same restriction enzyme to cut open bacteria plasmid in order to form complimentary sticky ends
3.insert insulin gene into plasmid using dna ligase
4. insert restriction plasmid into host bacteria
bacteria divide to produce insulin protein
how does the specific immune system work
pathogens have antigens that trigger antibodies to be produced by lymphocytes
leads to destruction of pathogen and memory lymphocytes are produced for secondary response
how to use microscope?
place slide on stage
set to lowest objective lens
move stage up
focus slide using coarse focus
change objective lens to higher
repeat focus process using fine focus
iodine solution is used to bind to starch and makes cellular structures more visible
how do vaccinations work?
weakened pathogens are injected into the body in order to stimulate white blood cells to produce antibodies
lytic cycle  
virus attaches to host cell
virus injects its genetic material into host cell
cell machinery of host cell produces viral components
cell bursts releasing new viruses to infect
lysogenic cycle  
virus attaches to host cell
injects genetic material into host cell
viral dna incorporates into host cell genome
virus remains dormant
host cell divides replicating
viral dna into each daughter cell
environmental changes causes the change to lytic cycle
viral dna exits hosts genome
lytic pathway begins
genetically modified organism have improved traits:
drought resistance
increased yield
herbicide tolerance
virus resistance
production of proteins
flood resistance
what is phagocytosis? 
when white blood cells engulf pathogen
tracks pathogen doen
binds to them
engulfs
physical and chemical barriers
skin secretes oil to kill pathogens
nose has hairs so mucus trap pathogens
lungs trachea and bronchiole are slathered in mucus to trap particles
to stop mucus building it’s lined with cilia that move mucus up to back of throat
stomach produces hcl with pH of 2 that acidic kills pathogen
conditions needed to grow bacteria
nutrient availability
moisture
oxygen
clear inhibition zone = pi r ^2
how do painkillers prevent neurotransmitters binding to receptors in a synapse? 
synpases are gaps between neurones
the electrical impulse reaches the synapse and the neurotransmitters diffuse across a synapse into the next neurone
a new impulse is initiated at a neurone
painkillers prevent neurotransmitters binding
new impulse not generated