IMMS Flashcards
what is mosaicism
cells within the same person have different genetic makeup (can be somatic or germline/gonadal)
what is gonadal/germline mosaicism
where more than one set of genetic information is found specifically within the gamete cells
what is heterochromia
variation in colouration
when does crossing over occur
prophase 1
what happens in prometaphase
- nuclear membrane breaks down
- microtubules invade nuclear space
- chromatids attach to microtubules
purposes of mitosis (3)
- growth
- replacing dead cells
- producing 2 daughter cells which are genetically identical to the parent cell
dominant characteristics
manifest themselves in a heterozygous state
the process in which mRNA is used to specify the amino acids required for protein formation is known as
translation
the process by which DNA is transcribed / copied into mRNA which then leaves the nucleus
transcription
where are ribosomes formed
in the nucleus
what causes sickle cell anemia
mutation which causes the substitution of an amino acid in the beta globin chain
in hypoxia, the abnormal HbS …
polymerises
the HbS structural change causes sickling by …
binding to the cytoskeleton
in sickle cell anemia, capillary occlusion is now thought to occur by …
endothelial damage causing multicellular (platelets, white cells) aggregates which occlude the capillary
in patients with SCD (sickle cell) an acute pain crisis is typically caused by capillary occlusion in the …
bone
sickle cell disease can be treated with hydroxyurea because it …
increases the synthesis of HbF (foetal Hb)
what is an oligosaccharide
a few units of a monosaccharide
bond between amino acids
peptide bond ( between amino and carboxyl groups )
what breaks peptide bonds
proteolytic enzymes eg proteases and peptidases
whats a proteoglycan
long unbranched polysaccharide radiating from a core protein (when sulphated they absorb a lot of water)
how to form an ester
lipid and alcohol
steroids
- regulate
- are used in
- regulate cell differentiation
- are used in cell signalling
whats the steroid nucleus
cholesterol
what are eicosanoids
chemicals synthesised from 20 carbon acids which cause inflammation
define a base
proton acceptor
how many litres of water in a 70kg man
- intracellular?
- extracellular total?
- interstitial?
- plasma fluid?
42L TOTAL
- intracellular 28L
- extracellular total 14L
- interstitial 11L
- plasma fluid 3L
is there more sodium in or outside the cell?
outside
is there more potassium in or outside the cell?
inside
what is used in calculating serum osmolarity?
sodium, glucose, BUN (blood urea nitrogen)
what is insensible fluid loss?
insensible fluid loss is loss that is not easily measured e.g. sweating, water lost from respiration, evaporation during abdominal surgery
what is sensible fluid loss?
sensible fluid loss is that which is easily measured e.g. urine output, vomit, fluid in surgical drains
albumin effect on oncotic pressure?
albumin increases oncotic pressure so fluid diffuses from the interstitial fluid into the blood
what influences the amount of ADH released?
plasma osmolarity
osmolality definition and units
the measure of how much substance has dissolved into another substance in mOsmKg-1
where is aldosterone made
adrenal cortex
what does aldosterone do
- steroid hormone released from the adrenal cortex in response to stimulation by angiotensin II
- it promotes sodium reabsorption and potassium secretion in the distal tubules of the kidneys therefore increases water reabsorption
what is the principal site of renin production?
juxtaglomerular cells
what causes renin to be produced?
decrease in perfusion pressure indicating fall in ECF volume
what does renin do?
converts angiotensinogen (produced by liver) to produce angiotensin I
what does acetyl cholinesterase (ACE) do?
converts angiotensin I to angiotensin II
where is acetyl cholinesterase (ACE) produced?
lungs
what does angiotensin II do?
- increases sympathetic activity e.g. vasoconstriction
- acts on posterior pituitary gland to secrete ADH when severely volume depleted
- acts on adrenal gland to stimulate release of aldosterone
where is ADH made
hypothalamus (but released from posterior pituitary)
what do eicosanoids do and what are they made from
cause inflammation and are made from 20 carbon acids
A and T nucleotides have how many hydrogen bonds between them?
3
what is the bond within a nucleotide that joins the phosphate to the sugar
ester bond
what is the bond within a nucleotide that joins the sugar to the base
glycosidic bond
what is the p53 gene
tumor supressor gene
what does topoisomerase do
unwinds the dna
what does dna polymerase do
reads the existing dna to create 2 new strands
what does dna helicase do
opens/unzips the dna
what direction does dna replication go in
5’ to 3’
what does primase do
make the primers involved in dna synthesis
what does it mean by the genetic code being degenerate
many amino acids are specified by more than one codon
what is the central dogma
dna–> rna–> protein
kDA unit??
kilodaltons
what is special about retroviruses eg HIV
they can do reverse transcription
what is transcription
when the dna is copied into mrna which then leaves the nucleus
what is rRNA
it combines with proteins to form 80s ribosomes
what does it mean when chromosome defects are described as paracentric eg inversions
they dont involve the centromere
deficiency in folic acid leads to ??
fragile x syndrome
what is the end of the chromosome called
telomere
what is a de novo mutation
a mutation in the germ cells
what is penetrance
the % of individuals with a specific genotype showing the expected phenotype
what is an autosome
any chromosome other than sex chromosomes that occur in pairs in diploid cells
what is homozygous
presence of identical alleles at a given locus
