Cell Reproduction Flashcards
How do cells reproduce?
Dividing
What are gametes?
Sex cells
sperm and ova
What does an ova and a sperm fuse toegether to create in sex?
Zygote
How do fungi and bacteria reproduce?
Asexually
Define the cell cycle
The period between the formation of a new cell and when it divides into daughter cells
Run through the cell cycle
G1 SYNTHESIS G2 MIITOSIS CYTOKENSIS
Where does DNA replication occur?
in the synthesis stage
What makes up the largest part of the cell cycle?
Interphase
Define Mitosis
A type of cell division in which two identical daughter cells are prodcued.
What are somatic cells also known as?
Diploid
What are the three functions of mitosis?
Growth
Repair
Asexual Reproduction
Summarise the process of mitosis
Chromosomes duplicate
Sister chromatids separate
Nucleus divides
What are the autosomes?
Chromosomes1-22
Male chromosmes
XY
Female Chromosomes
XX
What is chromatin?
The subtance that makes up chromastids
What does mitosis produce?
Two daughter diploid cells
What does meiosis produce?
4 daughter haploid cells
Explain interphase for mitosis
- Cell is performing whatever job it is designed to do
- DNA replicates and begin to condense at the end of interphase
What can be seen for the interphase stage on mitosis
Individuals cannot see te chromosomes yet they can see the chromatin blob
What happens in mitosis in prophase I
Chromosomes begin to shorten and condense and therefore become much easier to see
-Nuclear mmembrane breaks down thus allowing the chromsomes to move around the cell
What is formed during prophase?
A spindle forms which is controlled by the centrioles.
Explain what happens at metaphase I in mitosis
Spindle fibres latch onto the chromosomes and line along the eqautor.
The spindle fibres attach the to the centro meters
Explain what is happening in anaphase 1 in mitosis
Spindle fibres contract which spikes the chromosmes into seperate chromatids
the derogate chromastids are then drawer to either end of the cell
Explain what’s happening at telophase I in mitosiss
Two goes of chromosomes will unravel and become blobs of chromatin.
Nuclear membrane reforms and is create around the two groups
Define Meiosis
The division of diploid parent cells to produce four, non-identical haploid cells
What does meiosis produce?
Gametes
What type of division is meiosis
Reduction
diploid number
2n
haploid number
n
Explain a haploid cell
Contains a single set of chromsomes and has half the amount of the genetic materials
Explain a diploid cell
Two complete sets of chromosomes
What are homogenous pairs.
Chromosomes carrying the same gene
When are female gametes produced..
In development from zygote to child
When are male gametes produced?
constantly all throughout their life
Define crossing over
Involves the breaking and rejoining of chromatids
When does crossing over occurr?
Prophase I of meiosis
Define tetrad
A molecules in which is produced during crossing over
what is a chiasma
the crossing over and intersection point between two chromatids
Explain interphase for meiosis
DNA replicates in which each chromosome becomes a pair of chromatids
Explain Prophase I for meiosis
Chromosomes condense
Nuclear membrane fragment
Spindle is formed
Homologous pairs pair and up and cross over
What is the purpose of crossing over?
Genetic Variation
Explain what happens in metaphase I? for meiosis
Chromosomes line up. along the equator in homologous pairs
Anaphase I meiosis
homologous chromosomes seperate and one piece of each pair will move to either end of the cell
Telophase I for meiosis
Nuclear membrane begins to form
prophase II for meiosis
Nuclear membrane breaks down and spindles reform
Metaphase II for meiosis
Paired chromatids line the equator attached by a spindle to their centromere
Anaphase II
chromatids move to opposite ends of the poles due to spindles contracting
A telophase II for meiosis
Nuclear membrane reforms
Define reproduction
Production of futher members of the same species via asexual or sexual reproduction
Examples of axsexual reproduction
- Binary fission
- Mitosis
What is binary fission
-How prokaryotes replicate
explain binary fission
Single chromosome replicates , DNA polymerase replicates it.
What occurs in G1 phase>?
Cells double in size
What occurs in S phase
Dna and associated proteins replicate
What occurs in G2 phase?
Chromosomes begin to condense.
What is cytokinesis?
Follows telophase, daughter cells grow to reach regular size
Explain how crossing over leads to genetic variation (Recombnation)
In prophase 1 hoomologous chromosomes pair, make contact and can become intertwined.
Genetic material can be swapped for the corresponding material
This can lead to new combinations of genetic material on a chromosome
Define chiasma
The point of crossing over in prophase.
Explain how independent assortment can lead to variiation
Pairs of homologous chromosomes assort independently at metaphase 1 and this results in variation.
