194543
Description
Mind Map by tomking304, updated more than 1 year ago
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Created by tomking304
over 10 years ago
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BIOLOGY 2
- all sexually reproducing organisms
start life as single cell
- growth & development depends on replication of
this cell & its descendants - mitosis
- growth & development depends on replication of
this cell & its descendants - mitosis
- mitosis cannot generate cells
capable of sexual reproduction,
eg sperm & eggs
- if it did they would each have full
complement of chromosomes present in
parental cells, so embryo would have
twice as many chromosomes as their
parents cells & this number would double
at every generation
- potential problem of accumulating DNA
solved by meiosis - particular type of cellular
replication found only in cells that give rise to
gametes
- potential problem of accumulating DNA
solved by meiosis - particular type of cellular
replication found only in cells that give rise to
gametes
- if it did they would each have full
complement of chromosomes present in
parental cells, so embryo would have
twice as many chromosomes as their
parents cells & this number would double
at every generation
- karyotype - complement of chromosomes
in eukaryote cell defined as number, size,
shape & arrangement of organisms
complement of chromosomes
- different species, & sometimes different
populations within same species, can
have different karyotypes
- different species, & sometimes different
populations within same species, can
have different karyotypes
- set of chromosomes includes autosomes & in
some groups (incl mammals, bird, insects & some
flowering plants) sex chromosomes
- autosomes usually have same complement & arrangement of
genes in both sexes, whereas sex chromosomes differ between
male & females (F - XX, M - XY)
- number of chromosome sets in
individual's cell determines its
ploidy
- humans have 2 sets of chromosomes,
each comprising 23 chromosomes, so
karyotype is 2n = 46
- humans have 2 sets of chromosomes,
each comprising 23 chromosomes, so
karyotype is 2n = 46
- number of chromosome sets in
individual's cell determines its
ploidy
- autosomes usually have same complement & arrangement of
genes in both sexes, whereas sex chromosomes differ between
male & females (F - XX, M - XY)
- polyploid organisms have more
than 2 complete sets of
chromosomes
- very common in flowering
plants & occurs in some
fungi, fish, reptiles & insects
- new polyploids arise when
complete sets of chromosomes
fail to separate during meiosis
- very common in flowering
plants & occurs in some
fungi, fish, reptiles & insects
- genome - entire
complement of
organisms genetic
material
- sequence data of DNA from many
different organisms presents
opportunities to investigate changes to
genomes during course of evolution
- considerable diversity in
genome structure - size
& organisation - among
species investigated
- considerable diversity in
genome structure - size
& organisation - among
species investigated
- sequence data of DNA from many
different organisms presents
opportunities to investigate changes to
genomes during course of evolution
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