Control of cellular development
Human genome: 20000-250000 genes make 10000 proteins (1 gene can code for many
proteins)
- Introns (non coding)
- Exons (coding): joined together in diff ways after RNA polymerase has copied the
gene > diff protein structures
Homologous chromosomes
- pairs of chromosomes that control the same biological characteristic
- each pair:
- same shape + size1
- paternal chromosome + maternal chromosome
- diff no of chromosomes for diff species of organisms
- humans: 23 pairs of homologous chromosomes, 46 chromosomes in total
- size/complexity of organism unrelated to no of chromosomes 2
Diploid cells (2n) Haploid cells (n)
- contain both members of each - contain only 1 member of each
homologous pair of chromosomes homologous pair of chromosomes
- 2 sets of chromosomes - only 1 set of chromosomes
- examples - examples
- most somatic cells3 of - gametes sex cells
organisms body cells - ova / sperm @humans
Fertilisation: zygote > (divide) > embryo > (divide) > (after week 8) foetus
Epigenetic factors: genetic master genes and environmental influences
- Control the activation of genes and switching off of others (expression of genes)
Transcription factors: determine which area of DNA code is transcribed to mRNA, which
is used to make specific proteins that specialise cells
- eg. protein that stops RNA polymerase from copying another gene (repressor),
protein that helps RNA polymerase to copy another gene (activator)
1
23rd pair of chromosomes in males: diff shape + size
2
shrimp: 127 pairs, total 254
3
X mature red blood cells (NO nucleus!)
, - Internal cues (TF @cytoplasm of zygote differ in quantity/ratio and type in cells
made from diff areas of zygote), external cues (signalling from neighbouring cells,
temp)
Differentiation: switching on the right set of genes so the right proteins are made and the
cell becomes specialised with new abilities
Stem cells
- Able to divide and differentiate into other cell types and other stem cells
- Totipotent: can turn into any cell type
- Embryonic stem cells @morula
- Pluripotent: can turn into most cell types, except cells of placenta, umbilical
cord
- Mesoderm tissue (inner cell mass) of embryo, iPS Induced pluripotent
stem cells (specialised cells that have been turned back into
pluripotent cells)
- Multipotent: can only turn into a few cell types
- Adult somatic stem cells (eg. from bone marrow, muscles, liver, skin)
- Specialised (unipotent)
- Self renewal: (mitosis) produce replacement stem cell + specialised cell
Embryogenesis
Therapeutic cloning (regenerative medicine)
- Use of embryonic stem cells to produce healthy cells to be transplanted back into a
patient
- Denucleated donor egg cell + patient nucleus
, - NOT reproductive cloning
- ethical?
Benefits Risks
- Reduce rejection risk in transplants - Religious objections (playing God)
- No need to wait for human donor to - Possible risk of race to create the
die to donate organs first human clone (UN recs against
- Some success stories reproductive cloning X ratified by
all)
Prokaryotic and eukaryotic cells
Prokaryotic cells Eukaryotic cells
Similarities - bounded by cell membrane
- DNA as genetic material
Defining X membrane-bounded organelles Membrane-bounded organelles to
, characterist in cytoplasm compartmentalise diff functions
ic mitochondria, chloroplast mitochondria (respiration),
chloroplast (photosynthesis)
Organelles Flagellum, Pili, mesosome, Smooth ER, Rough ER, Golgi
Capsule, Ribosome, circular apparatus, Ribosomes,
bacterial chromosome, Plasmids, Mitochondria, Chloroplasts,
Cell wall, cell plasma membrane, Lysosomes, Cell plasma membrane,
conjugation tubes, (binary Nucleolus, Nuclear membrane,
fission) Centrioles, cytoskeleton
Differences - usually smaller - usually larger
- X true nucleus - true nucleus4
- DNA: lie free in cytoplasm - DNA: enclosed in nucleus
in nucleoid w/o nuclear with nuclear membrane
membrane - Ribosomes: some attached
- Ribosomes: lie free in to ER, some lie free in
cytoplasm cytoplasm
- Cell wall: present / absent - Cell wall: present in plant
- X cellulose cells, absent in animal cells
bacteria: peptidoglycan - (most) cellulose
(protein+carbs)
examples prokaryotes eukaryotes
prokaryotic cell (=unicellular) eukaryotic cell (≠multicellular)
- bacterial cells - plants, animals, fungi,
- archaea (earliest type of protists
organisms on Earth) - amoeba unicellular
4
nucleus surrounded by nuclear membrane
Human genome: 20000-250000 genes make 10000 proteins (1 gene can code for many
proteins)
- Introns (non coding)
- Exons (coding): joined together in diff ways after RNA polymerase has copied the
gene > diff protein structures
Homologous chromosomes
- pairs of chromosomes that control the same biological characteristic
- each pair:
- same shape + size1
- paternal chromosome + maternal chromosome
- diff no of chromosomes for diff species of organisms
- humans: 23 pairs of homologous chromosomes, 46 chromosomes in total
- size/complexity of organism unrelated to no of chromosomes 2
Diploid cells (2n) Haploid cells (n)
- contain both members of each - contain only 1 member of each
homologous pair of chromosomes homologous pair of chromosomes
- 2 sets of chromosomes - only 1 set of chromosomes
- examples - examples
- most somatic cells3 of - gametes sex cells
organisms body cells - ova / sperm @humans
Fertilisation: zygote > (divide) > embryo > (divide) > (after week 8) foetus
Epigenetic factors: genetic master genes and environmental influences
- Control the activation of genes and switching off of others (expression of genes)
Transcription factors: determine which area of DNA code is transcribed to mRNA, which
is used to make specific proteins that specialise cells
- eg. protein that stops RNA polymerase from copying another gene (repressor),
protein that helps RNA polymerase to copy another gene (activator)
1
23rd pair of chromosomes in males: diff shape + size
2
shrimp: 127 pairs, total 254
3
X mature red blood cells (NO nucleus!)
, - Internal cues (TF @cytoplasm of zygote differ in quantity/ratio and type in cells
made from diff areas of zygote), external cues (signalling from neighbouring cells,
temp)
Differentiation: switching on the right set of genes so the right proteins are made and the
cell becomes specialised with new abilities
Stem cells
- Able to divide and differentiate into other cell types and other stem cells
- Totipotent: can turn into any cell type
- Embryonic stem cells @morula
- Pluripotent: can turn into most cell types, except cells of placenta, umbilical
cord
- Mesoderm tissue (inner cell mass) of embryo, iPS Induced pluripotent
stem cells (specialised cells that have been turned back into
pluripotent cells)
- Multipotent: can only turn into a few cell types
- Adult somatic stem cells (eg. from bone marrow, muscles, liver, skin)
- Specialised (unipotent)
- Self renewal: (mitosis) produce replacement stem cell + specialised cell
Embryogenesis
Therapeutic cloning (regenerative medicine)
- Use of embryonic stem cells to produce healthy cells to be transplanted back into a
patient
- Denucleated donor egg cell + patient nucleus
, - NOT reproductive cloning
- ethical?
Benefits Risks
- Reduce rejection risk in transplants - Religious objections (playing God)
- No need to wait for human donor to - Possible risk of race to create the
die to donate organs first human clone (UN recs against
- Some success stories reproductive cloning X ratified by
all)
Prokaryotic and eukaryotic cells
Prokaryotic cells Eukaryotic cells
Similarities - bounded by cell membrane
- DNA as genetic material
Defining X membrane-bounded organelles Membrane-bounded organelles to
, characterist in cytoplasm compartmentalise diff functions
ic mitochondria, chloroplast mitochondria (respiration),
chloroplast (photosynthesis)
Organelles Flagellum, Pili, mesosome, Smooth ER, Rough ER, Golgi
Capsule, Ribosome, circular apparatus, Ribosomes,
bacterial chromosome, Plasmids, Mitochondria, Chloroplasts,
Cell wall, cell plasma membrane, Lysosomes, Cell plasma membrane,
conjugation tubes, (binary Nucleolus, Nuclear membrane,
fission) Centrioles, cytoskeleton
Differences - usually smaller - usually larger
- X true nucleus - true nucleus4
- DNA: lie free in cytoplasm - DNA: enclosed in nucleus
in nucleoid w/o nuclear with nuclear membrane
membrane - Ribosomes: some attached
- Ribosomes: lie free in to ER, some lie free in
cytoplasm cytoplasm
- Cell wall: present / absent - Cell wall: present in plant
- X cellulose cells, absent in animal cells
bacteria: peptidoglycan - (most) cellulose
(protein+carbs)
examples prokaryotes eukaryotes
prokaryotic cell (=unicellular) eukaryotic cell (≠multicellular)
- bacterial cells - plants, animals, fungi,
- archaea (earliest type of protists
organisms on Earth) - amoeba unicellular
4
nucleus surrounded by nuclear membrane
