Unit 1 Cell division, reproduction done Flashcards
Cell cycle
2 phases interphase and M phase
There are 2 M-phase types
Mitosis and meiosis both have 2 types, nuclear division and cytoplasm division.
Meiosis have 8 stages meiosis 1 and 2
Mitosis have 4 stages
Meiosis is from the Greek word (meioun) meaning to make smaller.
Mitosis
Occurs in body cells in all organisms
Except viruses. Ex: skin cells
Form 2 identical daughter cells
1 division round
4 phases of division
Leads to growth and repair and
no need in exam
zygote development
Diploid chromosomes number
(2 complete sets)
(Chr.# = to the one in the parent cell)
In greek
Prophase (pro means before or first)
Metaphase (meta = after)
Anaphase (Ana = up)
Telophase (Telo = end or completion)
Meiosis
Occurs in sex cells (ovary and testis) and occurs in plant, animal, and fungi kingdoms.
Form 4 unidentical daughter cells.
2 division rounds meiosis 1 and 2
no need for the exam:
The chromosome number of daughter cells is haploid (1 set of chromosomes either from the father or mother) on the other hand diploid have 2 sets 1 from the mother and 1 from the father.
Meiosis 1 Meiosis 2
Prophase 1 Prophase 2
Metaphase 1 Metaphase 2
Anaphase 1 Anaphase 2
Telophase 1 Telophase 2
Define reproduction and state its types.
The production of offspring by sexual or asexual process.
Define Asexual reproduction and state examples, advantages, and disadvantages.
A process resulting in genetically identical offspring from 1 parent, does not involve sex cells or fertilization.
Eg: Bacteria copy themselves in a process called binary fission.
Plants copy themselves using bulbs or tubers.
Advantages: Population can increase rapidly in the right conditions.
Time and energy efficient.
Disadvantages: Limited genetic variation which can cause a population suitable for only 1 habitat.
A disease can affect the whole population due to the same reason.
Define sexual reproduction and state examples, advantages, and disadvantages.
A process involving the fusion of the nuclei(plural of a nucleus which contains chromosomes) of 2 gametes(egg cells) to form a fertilized gamete (Zygot) producing a genetically different offspring.
Gametes have half of the number of chromosomes found in other cells, having only one copy of each chromosome (Haploid nucleus).
In humans, the sperm(male gamete) and the ovum(female gamete) are fused to produce 46 chromosome zygote (Diploid nucleus).
Most crop plants reproduce sexually in the same process but the chromosomes differ.
Advantages: Genetical variation in offspring causing adaptation to new environments and diseases is unlikely to affect the whole population.
Disadvantages: Takes time and energy to find mates. In plants, crops may be less quality.
