Lec 1 Flashcards
Cell Cycle and Chromosomes
composed of DNA, carrying the hereditary information (gene)
Chromosome
series of events which ncludes the growth, replication, and division of eukaryotic icells
Cell Cycle
Mitosis occurs in
somatic/vegetative cells
Flow of biological information
DNA > RNA > Proteins
Meiosis occurs in
gametic (reproductive) cells
occurs in somatic/vegetative cells
Mitosis
occurs in gametic (reproductive) cells
Meiosis
Cell Theory (5)
1.All living things are composed of cells.
2.All cells arise from preexisting cells through cell division.
3.Cells contain hereditary material, which is pass on to daughter cells during cell division.
4.The chemical composition of all cells is quite similar.
5.The metabolic processes associated with life occur within cells.
Why does cell division occur?
so that multicellular organisms can maintain a stable state, basically for growth, reproduction, and repair.
In unicellular organisms cell division occurs for?
occurs for the production of new organisms.
what happens in G2
cell prepares for division
what happens in G1
cell enlarges before DNA replication
“resting” or non-mitotic portion of the cell cycle
Interphase
what is interphase
“resting” or non-mitotic portion of the cell cycle
cell prepares for division
G2
cell enlarges before DNA replication
G1
The chromatins coils to from chromosomes
PROPHASE
microtubules forming mitotic spindle
PROPHASE
Chromosome consisting of two sister chromatids
PROPHASE
Centromere
PROPHASE
what happens in prophase
The chromatins coils to from chromosomes
– microtubules forming mitotic spindle
– Chromosome consisting of two sister chromatids
– Centromere
spindle poles, fragments of nuclear envelope, pair of
Kinetochore
PROMETAPHASE
The nuclear envelope breaks down. Microtubules connect
the kinetochores to the centrosomes
PROMETAPHASE
The nuclear envelope breaks down.
PROMETAPHASE
Microtubules connect
the kinetochores to the centrosomes
PROMETAPHASE
The microtubules line up the chromosomes at the cell’s
equator
METAPHASE
The chromatids separate, and the new chromosomes (each
derived from one chromatid) move toward the poles
ANAPHASE
begins at the plane of constriction forms
Cytokinesis
The separating chromosomes reach the poles. The nuclear
envelopes re-form and the chromatin decondenses
TELOPHASE AND CYTOKINESIS
main features of the different stages in meiosis
Larix.
Occurrence of mitosis
In all the body
cells including the
germ cells
Occurrence of meiosis
Only in the germ
(reproductive)
cells
Definition mitosis
It is an equational
division
Definition MEIOSIS
It is a reductional
division
No. of daughter
cells MITOSIS
2
No. of daughter
cells MIOSIS
4
PROPHASE in MITOSIS
Relatively few changes
PROPHASE in MEIOSIS
A series of changes in chromosomes distinguished into 5 substages
Relatively few changes
PROPHASE in MITOSIS
A series of changes in chromosomes distinguished into 5 substages
PROPHASE in MEIOSIS
Chromomeres in MITOSIS
Not visible in prophase
Not visible in prophase
Chromomeres in MITOSIS
Chromomeres in MEIOSOS
Visible in the leptotene stage of prophase-I
Visible in the leptotene stage of prophase-I
Chromomeres in MEIOSOS
Synapsis IN MITOSIS
Does not occur
Does not occur
Synapsis IN MITOSIS
Synapsis IN MEIOSIS
Occurs in zygotene of prophase-I
Occurs in zygotene of prophase-I
Synapsis IN MEIOSIS
Crossing over IN MITOSIS
Does not occur
Does not occur
Crossing over IN MITOSIS
Crossing over IN MEIOSIS
Occurs in pachytene stage of prophase-I
Occurs in pachytene stage of prophase-I
Crossing over IN MEIOSIS
METAPHASE IN MITOSIS
Chromosomes arrange along the equator
Chromosomes arrange along the equator
METAPHASE IN MITOSIS
METAPHASE IN MEIOSIS
Chromosomes arrange equally on either side of the equator in metaphase-I
Chromosomes arrange equally on either side of the equator in metaphase-I
METAPHASE IN MEIOSIS
Centromeres in ANAPHASE IN MITOSIS
Each centromere splits into 2
Each centromere splits into 2
Centromeres in ANAPHASE IN MITOSIS
Centromeres in ANAPHASE IN MEIOSIS
Centromeres do not split in metaphase-I
Centromeres do not split in metaphase-I
Centromeres in ANAPHASE IN MEIOSIS
Centromeres on METAPHASE IN MITOSIS
Orient towards the equator while chromatids orient towards pole
Orient towards the equator while chromatids orient towards pole
Centromeres on METAPHASE IN MITOSIS
Centromeres on METAPHASE IN MEIOSIS
Orient towards poles while chromatids orient towards the equator in metaphase-I
Orient towards poles while chromatids orient towards the equator in metaphase-I
Centromeres on METAPHASE IN MEIOSIS
TELOPHASE IN MITOSIS
Results in the formation of 2 daughter nuclei having the same number of chromosomes as that of parent cell
Results in the formation of 2 daughter nuclei having the same number of chromosomes as that of parent cell
TELOPHASE IN MITOSIS
TELOPHASE IN MEIOSIS
Telophase-II results in the formation of 2 daughter nuclei, each having half the number of chromosomes as that parent cells
Telophase-II results in the formation of 2 daughter nuclei, each having half the number of chromosomes as that parent cells
TELOPHASE IN MEIOSIS
CYTOKINESIS IN MITOSIS
Follows immediately after karyokinesis
Follows immediately after karyokinesis
CYTOKINESIS IN MITOSIS
CYTOKINESIS IN MEIOSIS
May or may not occur at the end of first karyokinesis
May or may not occur at the end of first karyokinesis
CYTOKINESIS IN MEIOSIS
CHROMOSOMES
molecule of DNA
molecule of DNA
CHROMOSOMES
sexual reproduction
two gametes fuse to a zygote
sexual reproduction
chromosomes of zygote = chromosomes of both gametes
why is a reduction of chromosome number necessary during formation of gametes
to avoid a doubling of chromosome numbers in each generation!
to avoid a doubling of chromosome numbers in each generation!
why is a reduction of chromosome number necessary during formation of gametes
reduction of chromosome numbers
meiosis
meiosis
reduction of chromosome numbers
DIPLOID
two homologous chromosomes
two homologous chromosomes
DIPLOID
GAMETE
haploid; one of the two homologous
chromosomes only
GAMETE
CHIASMATA (prophase 1)
recombination of genes on one
chromosome due to crossing over
recombination of genes on one
chromosome due to crossing over
CHIASMATA (prophase 1)
POLYPLOID
more than 2 homologous chromosomes
more than 2 homologous chromosomes
POLYPLOID
GENOME
complete set of non-homologous chromosomes
complete set of non-homologous chromosomes
GENOME
basic number x
number of non-homologous chromosomes
number of non-homologous chromosomes
basic number x
gametic number n
chromosome number of gametes
chromosome number of gametes
gametic number n
somatic number 2n
chromosome numbers of all somatic cells
chromosome numbers of all somatic cells
somatic number 2n
2n=2x(n=x)
diploid (eq)
diploid (eq)
2n=2x(n=x)
tetraploid (eq)
2n=4x(n=2x)
triploid (eq)
2n=3x(n=???)]
Chromosomes aberrations (4)
- Translocation
- Deletion
- Duplication
- Inversion
ANEUPLOIDY
change of basic number x caused by chromosome mutations
change of basic number x caused by chromosome mutations
ANEUPLOIDY
EUPLOIDY
change of number of genomes
change of number of genomes
EUPLOIDY
AUTOPOLYPLOIDY
set of chromosomes repeated several times
set of chromosomes repeated several times
AUTOPOLYPLOIDY
ALLOPOLYPLOIDY
several different chromosome sets
several different chromosome sets
ALLOPOLYPLOIDY
HYBRIDIZATION;
formation of non-reduced gametes
formation of non-reduced gametes
HYBRIDIZATION;
highly but not completely sterile
hybridization between closely related species
hybridization between closely related species
highly but not completely sterile
contribute to the evolution of new species
HYBRIDIZATION;
HYBRIDIZATION;
contribute to the evolution of new species
IMPORTANCE OF POLYPLOIDY
Polyploid organisms frequently develop…
* bigger cells and leaves: breeding
* reproductive isolation; species formation
* polyploid: more genotypes possible
* often associated with apomixis (asexual propagation through seeds)
* approx. 50% of all plants are polyploid
– grasses (75%)
– bamboo (48-74 chromosomes)
Chromosome numbers of Pinatae
- conifers: particularly big chromosomes
– Easy to observe and to count - Few polyploids
– but: Fitzroya, Sequoia sempervirens - little polymorphism within families
– but: Podocarpus
DIPTEROCARPS
- Different basic numbers (x)
– relation to phylogeny - Different basic numbers in some genera
– Hopea: 7, 10, 11 - Polyploid species:
– Hopea nutans, Shorea ovalis: 2n=4x=28
– Other Hopea spp.: 2n=3x - Chromosome polymorphisms:
– Hopea odorata (triploid trees; partially capable of
producing offspring through apomixis)
– Dipterocarpus tuberculatus
Chromosome numbers in Casuarina spp.
- approx. 60 species (Malayan and Australian region)
- some important species: C. equisetifolia
- most species diploid with 16 or 18 chromosomes
- chromosome polymorphisms:
– C. nana
– C. littoralis
Chromosomes Numbers of Tropical Forest Plants
- limited use of cytology in taxonomy
– Limited variation (Pinatae)
– too complicated (Meliaceae) - ploidy level important for further studies - e.g., gene markers; inheritance studies
- many polyploid plants also in the tropics - mainly Meliaceae; bamboos, grasses
- polymorphisms of chromosome numbers occur (effect on mating events and fertility???) - Swietenia spp.; Hopea odorata; Casuarina spp
- limited potential for practical applications - PopGR, breeding and conservation of GR of plants
- limited use of cytology in taxonomy
– Limited variation (Pinatae)
– too complicated (Meliaceae)
– Limited variation (Pinatae)
– too complicated (Meliaceae)
- limited use of cytology in taxonomy
polyploid plants also in the tropics
Meliaceae; bamboos, grasses
polymorphisms of chromosome numbers occur
Swietenia spp.; Hopea odorata; Casuarina spp
Swietenia spp.; Hopea odorata; Casuarina spp
polymorphisms of chromosome numbers occur
polymorphisms of chromosome numbers
effect on mating events and fertility???
effect on mating events and fertility???
polymorphisms of chromosome numbers
