Cel 1 flashcards
what is the genome
the complete set of genes in a cell
what is the proteome
the full range of proteins a cell is able to produce
describe the structure of mRNA
carries nucleotide message fom DNA to ribosome. Linear and single stranded because carries message of one patricular gene. length of the gene. has codons.
what are codons
sequence of 3 bases in mRNA.
what is the structure of tRNA
clove leaf shaped. 80 nucleotides in size and has anticodons.
what is the function of trna
carries specific amino acids to mrna and ribosome so amino acid can be put together in order dictated to ribosome by Mrna
what is transcription
the production of mRNA from DNA
what is the role of RNA polymerase
joining mRNA nucleotides
how does transcription result in prokaryotes
directly in the production of mRNA from DNA
how does transcription result in eukaryotes
the production of premNA which is then spliced to form mRNA
What is translation
the poduction of polypeptides from the sequence of codons carried by mRNA.
describe transcription
- DNA helicase unzips DNA breaking H bonds
- RNA polymerase enables binding of complementary activated RNA nucleotides (A,U,C,G) to template strands and forms bonds in sugar phosphate backbone
- mRNA synthesis when stop triplet reached on DNA
- In prokaryotes mRNA deataches from circular DNA and travels to ribosome in eukaryotes pre-mRNA spliced into mRNA
what is splicing
splicing removes introns and rejoins extrons which can be rejoined in different orders to create different proteins
describe translation
- ribosome binds to 2 codons of mRNA at start codon
- tRNAs, carrying specific amino acids and specific anticodons
- bind to complementary codons on mRNA
- ribosome forms peptide bond between amino acids
- ribosome moves along mRNA
- codon sequence determines amino acid order
what is the function of cartilage
supports and stops trachea and bronchi collapsing
what is the function of elastic fibres
stretch and recoil
what is the function of smooth muscle
contract and relax
what is the function of goblet cells
produce mucus to trap pathogens
what is the function of cilliated cells
sweeps mucus up
what is the essential feature of alveolar epithelium
made up of squamous epithelial cells which are single, flat covering and 1 layer, which means there is a short diffusion pathway for gas exchange to occur
what is ventilation
the movement of air in and out of lungs
what kind of process is inspiration
active process because ATP is required
describe inspiration
extenal intercostal muscles contract therefore ribs move up and out diaphram contracts and relaxes thus lung volume increases therefore air pressure decreases therefore air flows in down air pressure gradient
what kind of process is expiration
passive at rest- no ATP required because muscles relax
but active on exercise because internal intercostal muscles contract to expel a large amount of air
describe expiration
external intercostal muscles relax therefore ribs move down and in
diaphram relaxes therefore domed/raised
thus lung volume decreases
therefore lung air pressure increases
therefore air flows out down air pressure gradient
describe pathway taken by oxygen molecule from an alveolus to blood
across alveolar epithelium and then capillary endothelium
describe how oxygen in air reaches capillaries surrounding alveoli in lungs (details of breathing not required)
as a result of mass transport (movement of air down a pressure gradient through a tube) air moves down the trachea, the bronchi and the bronchioles to alveoli. the oxygen in the air then diffuses across the alveolar epithelium and capillary endothelium to get to capillary.
what is haemoglobin
a globular protein with a quaternary structure and each polypeptide chain has a haem prosthetic group
what is the function of haemoglobin
transpports by binding and releasing it
explain the shape of the oxygen dissociation curve
first oxygen binding changes tertiary structure therefore revealing next two binding sites which makes next two O2 molecules easy to bind to. The fourth O2 binding site is more difficult to bind to because 1/4 chance of binding to it therefore causing s shaped curve
what is the bohr effect
concept that partial pressure of co2 as well as partial pressure of O2 affects O2 saturation of Hb
what happens to oxygen dissociation curve when partial pressure of oxygen increases
haemoglobin has a decreased affinity for oxygen therefore dissociates more readily (shifts to right)
what happens to oxygen dissociation curve when partial pressure of CO2 decreases
decreased partial pressure CO2 causes Hb affinity for oxygen to increase therefore oxygen dissociates more readily
what happens to oxygen dissociation curve when an organism is in an oxygen poor environment
Hb has a higher affinity and therefore associates more readily so curve shifts to left
what happens to oxygen dissociation curve when organism is more metabolically active
Hb has a lower affinity and therefore dissociates more readily
how is DNA in prokaryotic cells
short, circular and not associated with proteins
how is DNA in eukaryotic cells
DNA molecules are very long, linear, and associated with proteins called histones. Together a DNA molecule and its associated proteins form a chromosome.
what is a gene
a gene is a base sequence of DNA that codes for the amino acid sequence of a polypeptide or functional RNA (including ribosomal RNA and tRNA)
what is the maths for bases to amino acids (proving triplet code)
4 to the power of the base
what is the ratio for number of bases coding for amino acids
3:1
what is the ratio for amino acids to bases
number of amino acids x3
why is genetic code described as universal
all organisms have DNA
why is genetic code described as non-overlapping
each base is in only one base triplet
why is genetic code described as triplet code
groups of 3 bases code for one amino acid
why is genetic code described as degenerate
each amino acid has at least one triplet code
what happens to remaining 44 bases (degeneracy)
several triplets code for 1 amino acid and some used as start/stop codons
