Topic 3 Flashcards
DNA synthesis in bacterial cell cultures has been investigated.
Describe how DNA is organised in a bacterial cell.
large) circular DNA [1]
DNA not associated with histone proteins [1]
(small/several) plasmids [1]
Located inside the cytoplasm / not inside a nucleus [1]
Describe what happens to lysosomes once their contents have been digested
Lysosome fuses with cell (surface) membrane [1]
Contents of lysosome released from the cell / exocytosis [1]
Cells produce lactate during anaerobic respiration.
Lactate travels in the blood to the
liver.
Liver cells can absorb lactate from the blood.
Deduce what happens to the lactate in these cells
lactate is {oxidised to form / converted to} pyruvate [1]
(pyruvate is) converted to {glucose / glycogen} [1]
(pyruvate / glucose)
Give two functions of the Golgi apparatu
Modifies proteins [1]
Forms vesicles [1]
Removes (some) water from the protein / concentrates the {protein / glycoprotein} [1]
What are the similarities and differences between prokaryotic and eukaryotic cells
- eukaryotic have membrane bound organelles such as mitochondria and Golgi
- size of ribosomes is lager in prokaryotes (80 instead of 70)
- eukaryotic do not have plasmid in cytoplasm
Describe what happens to proteins following translation until they are released from cell
-proteins are folded in the RER
- proteins are packed into vesicles
-protein is then modified in the Golgi
-chemicals released
- exocytosis out
Explain why enzymes that are incorrectly folded can’t carry out their function
- if the protein is not folded correctly the tertiary structure (3d shape) would be different
- therefore the active site of the enzyme would not bind with the substrate and not be bale to form a enzyme substrate complex
-therefore it would not be bale to catalyse the reaction
Describe the acrosome reaction
-it fuses with cell surface membrane of thesperm cell
- digestive enzymes are relased
-these break down the zone pellucid
Describe the cortical reaction
-fusion of cortical granules and egg cell surface membrane
- results in thinking of zone pelludica
- therefore preventing other stem from entering - cant reach cell surface. Membrane
Describe how offspring from the same parents can be genetically different
-each zygote is formed from different gametes
-each gamete contains different combination of alleles
- different combinations are due to independent assortent and crossing over during meiosis
Describe how meiosis leads to genetic variation in the gametes produced
-independent assortment produces non identical gametes
- crossing over between Chromatids of chromosomes
Explain why DNA is replicated before mitosis begins
- to ensure that there is one copy of each chromosome one in each daughter cell
- this will ensure daughter cells are genetically identical
Order of mitosis
I - interphase
P - prophase
M - metaphase
A - anaphase
T - telaphse
Describe prophase
- nucleus breakdown
- spindle fibres formed
-chromesomes condense
Describe metaphase
-attach to spindle fibres
- aligned on the equator of the cell
Describe anaphase
Split - centemores split and go to opposite ends
Describe telophase
Unravel - chromosomes unravel
Give the meaning of the term polygenic
- a characteristic showing continuous variation
- caused by multiple genes at a diffent loci
Explain how epigenetic changes affect the development of the tissue on the embryo
-DNA is wrapped around his tones
- modification of the histone affects binding of rna polymerase
- methylation of DNA affects transcription of genes produced
- this therefore alters gene expression
Ethics of stem cells
- embryonic stem cells are totipontent and can be used in a wider range if therapies
- source if embryonic stems has to be considered
- has moral ethical issues as it destroys embryos
- but needed for research
Scad zoned
Sperm reaches egg
Cchemicas realised from egg
Acrosome swells
Digestive enzymes break down
Zone pelludica - fuses with
Ovum csm
Nucleus enters ovum
Enzymes realised to thicken ZP
Nuclei fuse
Genes being switched on/off
Epigeonme determines which genes are transcribed
DNA wrapped around his tones which have
Chemical markers
In active genes if
DNA is tightly wound
Epigenetic markers copied during
Replication of DNA
Explain why a defective acrosome reaction may occur in male infertility
-egg cell is protected by the zona pellucida
-if acrosmes are defective the digestive enzyme wont be released
- therefore the zona pelludica will not break down and sperm will not be able to fuse with the egg
What is meant by the term sex linked disorder
- a disorder caused by a faulty gene
-located on x/y chromosome
-therefore the disease is more likley to be one gender
