Chapter 9 Cell Division Flashcards
What are the 2 types of cell reproduction?
1) Asexual reproduction
( Common in prokaryotic cells
does not involve fertilization)
2) Sexual reproduction
(Involves male and female cells
in most living things)
How does Prokaryotic cells divide?
They divide by Binary fission where the cells single chromosome duplicated and moves to opposite end of the cell and divide into 2
What are the 4 Stages of Binary Fission?
1)Single Chromosome will duplicated
2) Separate the copies
3) Continued growing of the cell and movement of the copies to the ends of the cell
4) it will than divide into 2 cells
What is the advantage and disadvantages of Asexual reproduction?
Advantages:
1) can reproduce without finding mates
2) can reproduce quickly as no time or energy is spent making gametes
Disadvantages:
1) They are genetically identical
2) if environment changes and affects 1 cell, all the cell will be affected with can wipe out the entire population
What is Haploid?
Haploid basically means cells consisting of only 1 set of chromosomes usually only in sex cells (1n)
What is Diploid
Diploid basically means cells that consist of 2 sets of a chromosome usually in somatic cells (2n)
What does the Nucleus do?
Control Centre of the cell
1) regulates growth
2) Basic metabolism
3) Reproduction
What does the Human Genome comprise of?
2 sets of 23 Chromosomes which equals to 46 chromosomes in total
44 autosomes and 2 sex chromosomes
What are the 4 reasons we sequence the human genome?
1) store gathered information to further study biological and medicinal study
2) understand the nature of proteins that genes code for
3) identify mutations in the gene which cause genetic disorders
4) new molecular medicine and new approaches
What are Chromosomes
1) Physical carriers of genes
2) located in nucleus
3) Compose of DNA wrapped around proteins called histones
4) when stain shows light and dark band areas
What are sister chromatids
they are the result of a chromosome undergoing DNA replication before cell division and are identical 1 chromatid will be distributed to 1 daughter cell
What are centromeres?
regions with attachment site for microtubules that will move the chromosome during division
Why do we need to wrap DNA around histones?
This is because we can condense the array of DNA sequences and make it more compact which is easier and more manageable to separate the cell during cell division
What is the Structure of Chromosomes?
1) p arm (short arm)
2) q arm (long arm)
3) centromere
4) chromatids
What dye do we use to smear stains on chromosome to reveal the G bands?
Giemsa dye
What does the Dark staining region represent on the chromosome?
late replicating and A-T Rich
What does the light/bright staining region represent on the chromosome?
early replicating and G-C rich
What is Human karyotype?
a systemized arrangement of the chromosomes of a single cell
What are genes?
Gene is a unit of information that code for 1 protein which also codes for 1 genetic trait
What are alleles?
1) each gene is control by a pair of alleles
2) alleles are alternative form of a gene
3) 2 alleles give 1 trait
What is Dosage compensation in Humans?
Because males only have 1 X chromosome and females have 2 X chromosomes there for the body have to compensate by muting one of the the X linked gene in females in early development, hence dosage compensation.
What are Barr Bodies?
Inactivated X chromosomes which shows a darkly staining spot in female cells
What is the 2 main parts of the cell cycle?
1) Interphase
2) Mitosis
What are the 3 phases of interphase?
1) G1 (growth)
2) S (Synthesis)
3) G2 (growth)
What are the 4 stages of mitosis?
PMAT:
1) Prophase
2) Metaphase
3) Anaphase
4) Telophase
What does the G1 Phase do?
1) grows in size and carry out normal metabolism
2) make more protein and ribosomes
3) duplicate organelles
what does the S phase do?
1) copies DNA
2) make proteins to wrap DNA
3) make more cell membrane material
What does the G2 Phase do?
1) Cell organelles divide
2) cell grows and prepare for mitosis
What does the M phase do?
Actual cell division through PMAT
What is mitosis?
division of cells that occur in somatic cells where 1 parent cells will divide into 2 daughter cells and are identical copies
What is the last phase after PMAT?
Cytokinesis
What happens in Prophase?
1)The Chromatin condenses and the chromosomes become thicker and more visible
2) The nucleolus disappears and nuclear membrane breaks down
3) Spindle apparatus forms from microtubules and attaches to centromeres of chromosome
What happens in Metaphase?
The nuclear membrane fragmentation/ breakdown completes and the duplicated chromosomes line up along the middle of the cell
(metaphase plate)
What happens in Anaphase?
Diploid sets of daughter Chromosomes separate and are pulled towards the opposite poles of the cell
What happens in Telophase?
1)During Telophase, the nuclear membrane and nucleoli starts to form at both poles
2)The chromosomes eventually uncoils to chromatin
What happens during Cytokinesis?
the cell forms cleavage (in animal cells) or cell plates ( in plant cells) and pinches itself apart to form 2 sets of diploid daughter cells
What is Meiosis?
It is when one parent cell divides into 4 daughter cells and it only occurs in reproductive cells
do not occur in prokaryotes. occur in animals in gametes and spores in fungi
What are the phases of meiosis?
Meiosis 1: P1M1A1T1
Meiosis 2: P2M2A2T2
What happens in meiosis 1?
the first chromosome have only a single chromatid before replication and after replication it doubles however chromosome number still the same. it than splits into 2 cells where the number of chromosome is half and the chromatid number remains the same as parent cell.
what happens in meiosis 2?
the 2nd meiosis division do no get any reduction and it is the same as mitosis. hence the final product will be 4 daughter cells with 23 chromosomes and 23 chromatids
what is the difference between meiosis 1 and meiosis 2?
1) meiosis 1 pulls apart homologous chromosomes in anaphase 1 instead of breaking the chromatids
2) it goes through interkinesis ( same as interphase but without DNA synthesis)
what is the difference between mitosis and meiosis?
Mitosis:
1) Only in somatic cells
2) produces 2 identical diploid daughter cells
3) homologous chromosome do no align and pair up
Meiosis:
1) only in reproductive cells
2) produces 4 distinct daughter cells
3) homologous chromosome pair up during prophase 1
What causes genetic diversity?
1) Synapsis linking of replicated homologous cells
2) crossing over: where identical sites (chiasma) breaks and swap with different segments
3) when homologous pairs arrange on the equator of the cell the harnessing of the centromeres is random
What are the 3 Chromosome structures?
1) Metacentric: Long p arm and long q arm
2) Submetacentric:
short p arm and long q arm
3) Acentric: satellite p arm normal q arm
What happens when there is a mutation during meiosis?
the Chromosomes do not separate properly during Meiosis 1 and 2 hence individual is born with less or more chromosomes
why is Chromosomal mutation more severe than gene mutation?
Because chromosome has more information and changes a lot of things compared to gene where it does not change as much
What is Karyotype (at meiosis )?
study about the arrangement of chromosomes according to their size and helps to diagnose presence of chromosome disorders
what are the 3 ways karyotype is done?
1) Giemsa Staining
2) FISH
3) Spectral type
What is Cytogenetics?
the study of chromosomes and their abnormalities
What are the 3 type of Chromosomal Abnormalities?
1) Euploidy: Normal
2) Polyploidy: Extra set in all the 46 chromosomes
3) Aneuploidy: Less or extra set of only a single chromosome
What are the 2 types of Aneuploidy?
1) Monosomy
2) Trisomy
What is the G0 phase and why it happens?
it is a phase where the cell is in a resting phase it happens because the cells do not receive adequate nutrients or resources for growing or division, hence it will stay in this state until it receives the appropriate signals
