15.02.2009 1 Attention! Test! Human chromosomes Normal karyotype Characterization of each chromosome Classification of chromosomes Pathologic karyotypes Nomenclature of chromosomes Methods of karyotyping (indications and limits) Sex chromatin Sex chromosomes X chromatin Y chromatin Barr body test (indications and limits) F body test (indications and limits) INHERITANCE OF GENETIC INFORMATION ERRORS OF MITOSIS AND MEIOSIS INHERITANCE OF GENETIC INFORMATION IS DONE VIA CHROMOSOMES FROM SOMATIC CELL TO SOMATIC CELL Replication of DNA Segregation of genetic material in metaphase (equationaldivision) FROM PARENTS TO OFFSPRING Gametogenesis Fecundation
17
Embed
INHERITANCE OF GENETIC INFORMATION ERRORS OF MITOSIS …bimogeum.ucoz.com/.../3_Errors_mitosis_meiosis_Eng.pdf · ERRORS OF MITOSIS AND MEIOSIS INHERITANCE OF GENETIC INFORMATION
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
15.02.2009
1
Attention! Test!
Human chromosomes Normal karyotype
Characterization of each chromosome
Classification of chromosomes
Pathologic karyotypes
Nomenclature of chromosomes
Methods of karyotyping (indications and limits)
Sex chromatin Sex chromosomes
X chromatin
Y chromatin
Barr body test (indications and limits)
F body test (indications and limits)
INHERITANCE OF
GENETIC INFORMATION
ERRORS OF MITOSIS AND
MEIOSIS
INHERITANCE OF GENETIC INFORMATION
IS DONE VIA CHROMOSOMES
FROM SOMATIC CELL TO SOMATIC CELL Replication of DNA
Segregation of genetic material in metaphase (equational division)
FROM PARENTS TO OFFSPRING Gametogenesis
Fecundation
15.02.2009
2
INTERPHASE
G1
S
G2
Synthesis of RNA and proteins
2n = 2c
Chrs – single-chromatid
Sysnthesis of DNA and
histones
Duplication of centriols
2n = 4c
Chrs – two-chromatids
Synthesis of tubulins and
mitogens
2n = 4c
Chrs – two-chromatids
MITOSIS
Prophase
Metaphase
Anaphase
Telophase
Condensation of chromosomes
Assembling of mitotic spindle,
nucleoli disappear
2n = 4c
Chromosomes in the middle of the
cell
2n = 4c
Longitudinal cleavage of
centromere
Chromatid disjunction
Simultaneous migration of
chromosomes 4n = 4c
Decondensation of chromatin,
cytokinesis
2n = 2c
15.02.2009
3
Mitosis represents an equationaldivision
because from a diploid cell (2n=46) will be
produced two diploid cells(2n=46)
All diploid cells (somatic) contain identical information, the same numbers of chromosomes.
Clone – group of cells resulted from
a single cell by mitotic divisions
46
46
46
46
46
46
46
46
46
46
46
46
46
46
46
Zygote
All cells are
identical;
resulted cells
will be also
identical
Biological importance of mitosis
Exact inheritance of information through generations
Growing of organism
Renewing of tissues
Regeneration of tissues
15.02.2009
4
STEPS OF INHERITANCE OF
GENETIC INFORMATION FROM
CELL TO CELL:
I STEP – DNA replication during S phase of interphase
II STEP – equal distribution of genetic information in daughter cells during anaphase
Errors of distribution of genetic material
during mitosis
A. Errors of DNA replication or repair which lead to:
- Gene mutations in somatic cells
- Mutant clones which may be inherited by different somatic cells
15.02.2009
5
Transversal cleavage of centromere
- Chromatid non-disjunction
- Anaphase lag
- If resulted cells are viable, they will produce clones of
mutant cells; resulted organism is called mosaic – it
contains different cell lines.
B. Errors of distribution of genetic material during anaphase as result of:
Mutant clones – genetically differentcells of one organism
46
46
46
46
47
45
46
46
46
46
46
47
45
47
45
Zygote
Resulted cells
will divide and
will produce
an mosaic
Mosaic 46/47/45
Chromosomal mosaics may be:
Autosomal
Gonosomal
Mixed
15.02.2009
6
- Ontogenetic stage
- During embryogenesis
- Congenital abnormalities
- Postnatal
- Cancers
- Involved chromosome- Chromosome with more (stronger) or less genes
- Gonosome or autosome (stronger)
- Tipul anomaliei- Monosomii (mai grav) sau trisomii
- Complete (mai grav) sau parţiale
Consequences of mosaics in phenotype depends on:
Transversal cleavage of centromere:
Causes:- Mutations in centromere DNA
- Errors in assembling of kinetocore
- Errors in assembling of mitotic spindle
- Multi-polar centriole
Consequences:
- Isochromosome p (ip) – duplications of genes in p arm and absence of genes in q
- Isochromosome q (iq) – duplications of genes in q arm and absence of genes in p