the cell cycle Flashcards
what happens during interphase?
the cell grows and duplicates all its organelles and DNA (the longest part of the cycle)
what happens during prophase?
DNA condenses and chromatids pair up, centrioles move to to the poles of the cell and the nuclear envelope breaks down
what happens during metaphase?
the chromosomes line up along the equator of the cell and spindle fibres form between the centromeres and centrioles
what happens during anaphase?
the spindle fibres contract and pull the chromatids apart using energy from ATP
what happens during telophase?
two nuclear envelopes reform and the chromosomes relax into chromatin
what happens during cytokinesis?
the cell cytoplasm splits in two and membrane reforms
what is chromatin?
relaxed DNA
what is a chromatid?
one half of a duplicated chromosome
what is a chromosome?
condensed DNA wrapped around histone proteins
what is the centromere?
the point at which chromatids attach to each other
what are centrioles?
paired organelles found at the poles of a cell
what are spindle fibres?
a type of microtubule, also known as the spindle apparatus, which pull chromatids apart
how does binary fission take place?
the organelles and DNA in a bacterium duplicate and fuse to the cell wall, and are pushed apart by new membrane during cytokinesis
how do viruses repicate?
they attach to a host cell using attachment proteins and inject their nucleic acid into it, the host cell produces and assembles viral components and the cell eventually bursts when enough are produced
what is a gene mutation?
a mutation which only affects one gene
what is a chromosome mutation?
a mutation which changes an entire chromosome, or adds an extra one
what is a silent substitution mutation?
a gene mutation which codes for the same amino acid as the non mutated version, due to the genetic code being degenerate
what is a missense substitution mutation?
a gene mutation which codes for a similar amino acid, which may or may not leave the protein fuctional
what is a nonsense substitution mutation?
a gene mutation which codes for a stop codon and ends the polypeptide
what is a deletion mutation?
a gene mutation which deletes a base and results in a left frame shift, affecting every amino acid after, due to the genetic code being non-overlapping
what is polyploidy?
a chromosome mutation which results with 3 chromosomes for each homologous pair
what is non-disjunction?
a chromosome mutation which results in gametes with one more or less chromosome than is usual (eg. downs syndrome)
what is a mutagenic agent?
a factor which increases the likelihood of mutation
what is the natural spontaneous mutation rate in humans?
one or two mutations in every 100,000 genes per generation
what is meiosis?
the method of cell replication used to make gametes
what is the locus of a gene?
the position of the gene in a chromosome
what is an allele?
one of the different forms of a gene
what is crossing over?
when homologous chromosomes get tangled in a chiasma to form a bivalent during meiosis (only in M1 and A1)
what is independent segregation?
when chromosomes line up in homologous pairs during meiosis anaphase and are pulled to each side
what is intraspecific mutation?
mutations within a species
what is interspecific mutation?
mutation between multiple species
what is directional selection?
evolution which acts against one extreme in a range of phenotypes
what is stabilising selection?
evolution which acts against both extremes in a range of phenotypes
what order does the cell cycle go in?
interphase, prophase, metaphase, anaphase, telophase, cytokinesis
what order does the cell cycle go in?
interphase, prophase, metaphase, anaphase, telophase, cytokinesis
