2D Flashcards
What are mutations
Change in nucleic acid sequence (DNA and RNA)
Mutation is inherited
Germline
Mutation is not inherited
Somatic
Small mutation
Gene level
Big mutation
Change on chromosomal level
Effect of altered gene sequence
Change amino acid sequence of polypeptide=> variation of phenotype (effect can be harmless or harmful or beneficial)
This is the main source of evolution (natural selection favours beneficial mutation)
Genetic mutation originally in ____ if heritable
Gametes so it become heritable, ex: sex influenced trait…autosomal dominant traits dependent of sex (so male express it and females dont like baldness)
SOmatic mutation, where
In all cells EXCEPT GAMETE=> NOT heritable
-mutation in progenitor cell and all other daughter cell express mutation,ex: cancer cells, expressed as sector like part of puzzle not whole
Base substitution
Small scale mutation
Single nucleotide change as a result of point mutation
Insertion
Small scale mutation
1+ base pairs added in sequence during DNA replication=frameshift mutation
Deletion
Small scale mutation
1+ base pair skipped during DNA replication usually=> frameshift mutation
Transition
Small scale mutation
Purine-> purine or pyramide-> Pyrimidine change
Transvertion
Small scale mutation
Purine to Pyrimidine or Pyrimidine to purine change
Missense mutation codon change effect
Aka non synonymous (change sense codon to sense codon for diff a.a.)
Change in a.a.
Nonsense mutation change effect
Aka premature step (change sense codon to stop codon)
Sense codon change into stop codon (truncated polypeptide)
Silent mutation change effect
Aka synonymous codon change (change sense codon to another codon for same a.a.)
Does NOT change a.a., why? Degeneracy of genetic code
Frameshift mutation effect
Aka insertion or deletion of small number of base pairs
Alter reading frame
WHat type of mutation is sickle cell anemia
Missense mutation (beta hemoglobin gene=> 6th a.a. Change from glutamic acid to valine)
R.B.C. Deficiency in O2 exchange, clog arteries, circulatory problems= higher risk of heart attack and stroke
Large scale chromosomal mutation types
- Depletion
- Duplication/amplification
- Translocation
- Inversion
Depletion
Large scale mutation
Loss of genes
Duplication/amplication
Large scale mutation
Increase dosage of gene
Translocation
Large scale mutation
Interchange of genetic part from non homologous chromosomes
Inversion
Large scale mutation
Reversing orientation of segment of chromosome
Spontaneous mutation
Naturally occurring mutation caused by replication errors and spontaneous lesions (de-ruination and deaminaion of bases)
Induced mutation and types??
Natural (environmental) or artificial (agent/not agent), cause mutation at much higher rate than spontaneous mutation
Types:
1. Mutagen… induce mutation by: replacing,alter, mispair, or damage (no longer pair with other base) base
2. Base analog… mimic bases and incorporates into DNA (cause mispairing during DNA replication, ex: 5-bromouracil pair with A)
3. Chemical… alter base structure=>mais-airing (alkylating and intercalating. Agents benzopyrene)
4. Damage to base (UV)
Allele
1 of diff for of gene (sequence variation)= diff phenotype
Wild-type allele
Normal form of gene and standard in lab
Loss of fxn allele
Mutation that reduce/eliminate gene fxn/expression
Gain of fxn allele
Mutation that enhance gene fxn/expression
What is a cell cycle
Set of process 1 cell grows and divides into 2 daughter cells
G1 and G2
Aka gap phases
Synthesis of proteins, RNA< metabolites
Sphase
DNA replication
M phase (mitosis)
Nuclear division
Cytokinesis
Cell division
G0
Resting phase (most adults are constantly in this state)
Eukaryotic cell cycle steps
1.G1 phase
2. S phase (DNA synthesis)
3. G2 phase
4. M phase (mitosis and cytokinesis)
5. G0 or G1
What does the progression of the cell cycle depend on
Activation of cyclin dependent kinase (CDK)… bound to cyclin subunit in each phase of cell cycle
Regulation of eukaryotic cell cycle
- DNA damage (G1/S) checkpoint…is DNA good for replication
- DNA replication (G2/M) checkpoint… is DNA fully replicated before mitosis
- Mitotic spindle checkpoint… are chromosomes aligned properly in metaphase
What is cancer and how is it caused
Malignant growth
Caused by uncontrolled cell division and altered expression of multiple genes as result ofmutations
What mutated genes are implicated in cancer
1.oncogenes:+ regulators in cell cycle (gain of fxn) including cyclin D/E (gene amplification), cdk4 allele (insensitive to inhibition)
2.tumor suppressor gene (- regulation of cell cycle and loss of fxn)
3. Inactivated p53 gene
.n
Haploid number of chromosomes
2n
Diploid number of chromosomes
Homologous chromosomes
Maternal and paternal pair of chromosomes
What is the same between homologous chromosomes??
A) # genes
B) order of genes
C) allele
A) and B)
**alleles can be diff
Mitotic cell cycle 1
G1->G2->prophase
What is G1 and its components
2n and 4 chromosomes… 1 chromatid per chromosome
What steps brings G1->G2 in mitotic cell cycle I
DNA replication
Chromosome not visible
Centriole duplication
G2 components
2n, 4 chromosomes, 2 chromatines/chromosome
Steps bringing G2 to prophase in mitotic cell cycle 1
-duplicated chromosomes condense and become visible with sister chromatids
-duplicated centrioles (centrosomes) move apart and form mitotic spindles
-nuclear envelope breaks down
Prophase components
2n,4 chromosomes, 2 chromatids/chromosome
Steps of mitotic cell cycle II
1.prometaphase
2. Metaphase
3. Anaphase
Steps bridging prophase to prometaphase
-kinetichore of sister chromatid is attached to spindle microtubule
-chromosomemove to equator of cell
Prometaphase components
2n, 4 chromosomes, 2 chromatids/chromosome
Prometaphase to metaphase
All chromosomes aligned at equator (metaphase plate)
Chromises attached to opp. Poles under tension
Metaphase components
2n, 4 chromosomes,2 chromatids/chromosome
Metaphase-> anaphase
Cohesin degraded
Sister chromatid and centromere separate to poles (spindle microtubule shortened)
Centrosome move further apart in anaphase B (microtubule lenghtened)
Mitotic cell cycle III
- Telophase
- G1
Anaphase-> telophase
-chromosome clustered at opp poles and decondensing
Nuclear envelope reforms around chromosomes
Cytoplasm begins to divide by furrowing (cytokinesis)
Telophase
4n
8 chromosomes
1 chromatid/chromosome
Telophase-> G1
2 daughter cells that are genetic duplicates of parental cell
G1 components
2n, 4 chromosomes, 1 chromatid/chromosome
Binary fission replication begins at
Origin
In binary fission where is the bacterial chromosome (template and daughter) attached
Inner membrane
Steps of binary fission
- Bacterial chromosome attached to inner membrane
- Cell elongates and bacterial chromosomes separate
- Inward growth og plasma membrane and partition of new cell wall=> dividing replicated DNA
- Produce 2 daughter cells (works cause 1 chromosome)
Meiosis I steps
- Germ cell (2n, 4 chromosome, 1 chromatid/chromosome)
-premeiotic DNA replication- - Germ cell (2n, 4 chromosome, 2 chromatid/chromosome)
- Prophase I (condensation of chromosomes, synapsis, recombination)
4.prometaphase I - Metaphase I
- Anaphase I
- Anaphase II
- Telophase I
What is condensation of chromosomes for meiosis I
Chromosomes condense to thread. 2 sister chromatid/thread
What is synapsis of chromosomes for meiosis I
Homologous chromosomes come together and pair
What is recombination of chromosomes for meiosis I
While paired,chromatids of homologous chromises undergo recombination by exchanging segments
What is prometaphase I of chromosomes for meiosis I
Nuclear envelope breaks down, spindle moves into nuclear area, kinetochore connect to chromosome
Synaptoemal complex
Non sister chromatids from 2 homologous chromosomes attached by this protein structure
Recombination
Non sister chromatids éxhcnage pieces
Recombination in eukaryotes
- Homologous chromosomes align during prophase I and exchange sections of non-sister chromatids during crossing over
A) precise breakage
B) equal exchange
C) repair breakage after - New chromatid with various combos of genes/alleles
Meiosis I overview
Aka reductional division
-# of homologous pair of chromosomes is reduced from 2 in parental cell-> 1 in daughter cell
-chromosome # is haploid but 2 chromatids/chromosome
-sister chromatids nad centromeres do not split unlike mitosis and meiosis II
-sister chromatids no longer identical (crossing over)
Interkinesis
Between meiosis 1 and 2
No DNA replication between first and second meiosis division
Meiosis 2 steps
1.Prophase II
2. Prometaphase II
3. Metaphase II
4.Anaphase II
5. Telophase II
Prophase II
Chromosomes condense and a spindle forms
Prometaphase II
-nuclear envelope break down
-spindle enter nuclear area
-kinetochore microtubule from opp spindle pole attach to kinetochore of each chromosome
Metaphase II
-movement of spindle microtubule align the chromosome on metaphase plate
Anaphase II
-spindle microtubule separate 2 chromatids of each chromosome and deliver to opp spindle poles
Telophase II
Chromosomes begin decondensing
Spindle disassemble
New nuclear envelope form
Between meiosis 1 and 2 is there DNA replication
NOOO
When do centromeres and sister chromatids separate
Anaphase II
Meiosis II result
4 cells produced with haploid # of chromosomes 1 chromatid/chromosome…not identical due to crossing over and random assortment
