voice of the genome Flashcards
formula to work out how many possible combos of chromosomes in gametes
2^n
n is no of pairs of homologous chromosomes
what does meiosis produce
gametes
4 genetically different haploid cells
what is crossing over
homologous chromosomes pair up to form bivalents
non sister chromatids can cross over and get entangled at chiasmata
results in new combo of alleles
what is independent assortment
homologous chromosomes arranged randomly on equator
pulled to opposite poles
diff allele combos produced
what is a diploid cell
has 2 copies of each chromosome
what is a haploid cell
has 1 copy of each chromosome
what is the effect of calcium ions on a sperm cell
cause the acrosome reaction to occur before the sperm cell reaches the egg
what is the acrosome reaction?
digestive enzymes from acrosome digest zone pellucida so sperm can enter egg cell
what is the cortical reaction
cortical granules in the egg cell release chemicals that cause the zone pellucida to harden
preventing more sperm from entering
what is formed when sperm and egg nuclei fuse
dipole zygote
what does the sperm cell mid piece contain lots of and why
mito
provide energy for flagella movement so can swim to egg
is an egg or sperm cell larger
egg
what is the function of follicle cells in an egg cell
protective coating
what is a gene
section of DNA that codes for a polypeptide/ protein
what is a locus
position of a gene on a chromosome
what is an autosome
a chromosome that is not a sec chromosome
what is autosomal linkage
2 or more genes on same autosome do not assort independently during meiosis
linked and stay together
passed onto offspring together
what are the female sex chromosomes
XX
what are the male sex chromosomes
XY
what is a stem cell
undifferentiated cell that can divide by mitosis an unlimited amount of times
what can totipotent stem cells differentiate into
embryonic
extra embryonic (placenta, umbilical cord)
what can pluripotent stem cells differentiate into
embryonic
what can multi potent stem cells differentiate into
adult stem cells
what is the process of cell differentiation
under certain conditions, some genes in a stem cell are activated
mRNA only transcribes from activated genes
mRNA translated to form proteins
protein structure responsible for modifying cell
what are transcription factors
protein that controls expression and therefore transcription of genes by binding to a specific region of DNA
what are activators
transcription factors that increase the rate of transcription
help RNA polymerase bind to DNA at start of gene
what are repressors
transcription factors that decrease the rate of transcription
stop RNA polymerase binding to DNA at start of gene
what is the promotor region
DNA sequence that RNA polymerase initially binds to
how is gene expression controlled in prokaryotes
transcription factors binding to operons
what is an operon
a section of DNA that includes:
cluster of structural genes transcribed together
promotor region
operator region (where transcription factors bind)
maybe regulatory genes that code for activators or repressors
what is the function of lactase
breaks down lactose so it can be used as an energy source in bacterial cells
what does the lac operon control
production of enzyme lactase
what happens when lactose is absent in prokaryotes
regulatory gene transcribed and translated
lac repressor protein produced
binds to operator region
RNA polymerase cant bind to promotor region
no transcription of structural genes
no lactase enzyme synthesised
what happens when lactose is present in prokaryotes
bac uptakes lactose
lactose binds to 2nd binding site on repressor protein
repressor protein shape distorts, cannot bind to operator region
RNA polymerase binds to promotor region
transcription
mRNA from all 3 structural genes translated
lactase produced
lactose broken down, used for energy
what is the role of the RER
process proteins made on ribosomes
what is the structure of the RER
formed from folds of membrane continuous with the nuclear envelope
surface covered in ribosomes
what is the function of the SER
production, processing and storage of lipids, carbohydrates and steroids
does the SER have ribosomes on its surface
no
what is the role of the Golgi body
modify proteins and lipids before packaging them into Golgi vesicles
what is the Golgi body made of
flattened sacs of membrane
how can the Golgi body be distinguished from the SER
by its regular, stacked appearance
it can be described as looking like a wifi symbol
what is the function of lysosomes
contain hydrolytic enzymes
break down waste materials
do new proteins go to the RER or Golgi first
RER
is DNA positively or negatively charged
negatively
do epigenetic occur in prokaryotes or only eukaryotes
only eukaryotes
what could cause epigenetic changes
stress
diet
exercise
toxins- smoking
what is methylation
methyl groups bind to DNA
methyl is positively charged and DNA is neg so they attract and DNA is tightly coiled to form heterochromatin
transcription factors cant bind to DNA
increased methylation inhibits transcription
what is acetylation
acyl groups bind to histone proteins
acyl groups are negatively charged like DNA so they repel and DNA isn’t tightly coiled
transcription factors can bind to DNA
decreased acetylation inhibits transcription
are epigenetic changes heritable
yes
for drug testing, what do modern preclinical trials test on
human tissues
animals
for drug testing, what occurs in phase 1 of clinical trials
small group of healthy individuals
monitor side effects
find correct safe dosage
for drug testing, what occurs in phase 2 of clinical trials
tested on patients
for effectiveness
placebos
in a double blind trial
for drug testing, what occurs in phase 3 of clinical trials
compare to existing drugs
patients in 2 groups
double blind trial
