physiology Flashcards
what order does DNA replication occur from? what are the two strands called? what is the joining enzyme called?
5’ to 3’. lagging and leading. DNA polymerase.
How are okazaki fragments formed?
DNA polymerase joins nucleotides in the 5’ - 3’ direction on both sides so the leading strand is formed in a single strand whereas the lagging strand forms fragments because DNA polymerase forms smaller fragments which lair have to be joined by DNA ligase.
what does helicase do? what does topoisomerase do? what does ligase do? what does primase do? what does nuclease do?
unzips DNA. relieves stress of supercoiling. joins okazaki fragments. catalyses formation of a primer. a primer is necessary for DNA replication as it acts as a starting point for DNA synthesis. DNA polymerase can only add to an existing piece of DNA. chops DNA when not needed.
what are steroids? what are the two types?
drugs that mimic natural hormones. anabolic = regulate manufacture of testosterone. corticosteriods = produces in adrenal gland.
what is mitosis? describe the phases of mitosis
production of two genetically identical cells. PROPHASE = chromatin condenses into chromosomes and centrosomes move to the opposite poles of the cell. PROMETAPHASE = nuclear membrane starts to break down and chromatids attach to the microtubules invading the nuclear space. METAPHASE = nuclear membrane breaks down completely and chromosomes line up along the metaphase plate. ANAPHASE = sister chromatids split apart at the centromere and move to the opposite poles of the cell. TELOPHASE = nuclear membrane forms around each set of chromatids and the chromosomes turn to chromatin again. cytogenesis starts (separation into two separate cells)
describe the phases of the cell cycle. how long does each phase take?
M = mitosis (1 hour). G1 = growth phase 1, production of organelles (6-12 hours). S = DNA replication from 2n to 4n (6-8 hours). G2 = second growth phase (3-4 hours). production of organelles and protein synthesis.
describe the first meiotic division.
replication occurs before so the cell is 2n (46 chromosomes). in metaphase 1, homologous chromosomes line up at the metaphase plate. crossing over occurs which produces recombinant DNA. microtubules attach to each chromosome and pull them to opposite poles of the cell. the rest occurs as the same as mitosis. the two daughter cells are 2n (23 chromosomes)
describe the second meiotic division.
replication does not occur before the second division. therefore is begins as 2n (23 chromosomes). the chromosomes line up on the metaphase plate and sister chromatids are pulled apart. this cell division forms 23 chromosomes = n.
what is the difference between male and female meiosis?
male = produces 4 same sized gametes, division begins at puberty. female = produces one dominant ova and 3 polar bodies, ova has all cytoplasm. meiotic process begins in utero but pauses until ovulation.
what is an oogonia?
after 30 mitotic divisions.
what is nondisjunction? what is an example?
failure of chromosomes to separate correctly. e.g. downs syndrome = 3 x 21
what is gonadal mosaicism?
more than one set of genes being present in one individual due to a mutation of a germ cell in the ovaries or testes. if mutated cell is fertilised > child could have genetic condition even if it isn’t in either parents own DNA.
describe the process of DNA replication.
CDNA uncoils by topoisomerase enzyme. DNA unzips by helices enzyme. Primer attaches and DNA polymerase forms DNA. two new strands of DNA are semi-conservative they each contain a template strand and one new strand.
what are the two parts of DNA?
genes which code for the production of proteins. and extragenic DNA that codes for the production of tRNA, rRNA etc.
what are the parts of a gene?
promoter, exons and introns. During transcription the entire gene is coded for in mRNA. introns are cut out by splicing and exons are joined together to form a coding strand of mRNA.
what is the underlying mechanism for genetic disorders concerning crossing over?
DNa lining up incorrectly and the wrong genes crossing over. an individual can end up with two of one gene and none of another.
describe the terms: genotype, phenotype, autosomal dominant, autosomal recessive, X-linked dominant/recessive, kareotype, autosomal, imprinting genes, dizygous and monozygous.
genotype = genetic constitution of an individual. phenotype = physical characteristic expressed. autosomeal dominant = only need one fault allele of a numbered chromosome to have the condition. autosomal recessive = need two of the fault allele to express the condition. X-linked dominant/recessive = need one faulty X to be affected, need two faulty Xs to be affected or only one if a boy, kareotype = entire set of 46 chromosomes, autosomal = numbered chromosome, imprinting genes = 1 allele can be switched off, dizygous = nonidentical twins and monozygous = identical twins.
give examples of these: autosomal dominant, autosomal recessive, X-linked dominant/recessive.
huntingtons, cystic fibrosis, rickets, haemophilia.
give the life spans of the following cells: nerves, skeletal, bones and tendons, RBCs, WBCs, platelets, colon cells, skin cells.
life time, almost all your life, years, 120 days, 6 hours, 7-10 days, 4 days, 2-3 weeks.
give the functions of the nucleus, mitochondria, golgi bodies, RER, SER, lysosomes, peroxisomes, and vesicles.
nucleus = houses most of the genetic material of the cell. controls gene expression, production of proteins, what enters and leaves the cell, houses nucleolus’ that make rRNA. RER = protein translation and synthesis. SER = synethsis of lipids. Golgi body = packaging pro tines. first level receives protein, second level phosphorylates/adds sugars, third level releases in a vesicle. lysosomes = hydrolytic enzymes for breakdown. peroxisomes = enzymes that will oxidise long chain fatty acids so can damage cell membranes. vesicles = carry molecules around cell and store.
what are the 3 types of cellular filament?
microfilaments - actin (5), microtubules - tubulin(25), intermediate(10),
give examples of macromolecules.
haemoglobin, collagen, glycogen, DNA, rhodospin - eye pigment.
what are the two types of bond for protein and sugars? where are they found?
peptide, glycosidic - joins and OH with an NH2 or OH - found in DNA.
what is the difference between an aldehyde and a ketone.
aldehydes - c=o on end. ketone - c=o on middle C.
What form of sugar can we absorb and digest?
D form.
what is a glycosaminoglycan? what is a proteoglycan?
long unbranched chain of a repeating disaccharide unit. protein attached to a glycosaminoglycan.
what are the main components of phospholipid bilayers?
channel proteins, spingolipids, phospholipids, glycoproteins, cholesterol.
what are saturated and unsaturated fatty acids? what are they at room temp?
saturated = no double bonds, fats. unsaturated = double bonds, oils.
what are purines and pyramidines?
purines = double ring, Adenine and Guarnine. pyramidines = Thymine and Cytosine.
what form of amino acid do we use? what determines their charge? what are polar amino acids? what are non-polar amino acids?
L form. the side chain, can determine polarity. ones that move when put in an electric field. side chain doesn’t contribute to charge.
describe the 4 levels of protein structure.
primary = chain of amino acids. secondary = beta pelted sheets or alpha helices, with H bonds. tertiary = disulphide bridges present, hydrophobic/phillic parts, ionic bonds. quaternary = more than one protein chain.
describe the 4 forces/bonds.
WdV = weak, arise from fluctuating electrical charges. Hydrogen = dipoles, stronger that WdV. Hydrophobic = non-polar, pack tightly in centre. disulphide = S-S strong.
what is a coenzyme?
organic structure that helps an enzyme function. e.q. collapse.
what is the innate immune system?
immune system which is the first line of defence and doesn’t change throughout your life, you are born with it and it does not alter. doesn’t contribute to long term immunity.
