Chapter 2: Cell division Flashcards
What are haploids?
Cells such as sex cells that only contain 1 pair (23) chromosomes. The opposite are diploids
What are chromosomes?
The coils in our cells that DNA is stored in. Healthy humans usually have 46
What are allelles?
Different versions of the same gene. For example, the gene for eye colour has an allele for blue eye colour and an allele for brown eye colour. For any gene, a person may have the same two alleles, known as homozygous or two different ones, known as heterozygous.
What is a gene?
A section of a chromosome that contains coded instructions to create a protein
What is mitosis?
The process in which a cell divides, creating 2 identical daughter cells
How many stages are there in mitosis?
There are 6 stages in mitosis, excluding the interphase
What is interphase?
The step in which the cell spends 90% of its life, preparing for mitosis. The chromosomes make copies of themselves, meaning you get 92 chromosomes
What is the first step in mitosis?
The first step is the prophase, the step in which all the material inside the nucleus (chromatin) condenses. The mitotic spindle also forms, the spindle made of long proteins that controls where in the cell the DNA should go
What is the second step in mitosis?
The second step is prometaphase, the step in which the nuclear envelope breaks down
What is the third step in mitosis?
The third step is metaphase, the phase in which the chromosomes line up in the middle of the cell and become attached to the spindle fibers
What is the fourth step in mitosis?
The fourth stage is anaphase, the phase in which the chromosomes separate at the centromeres, and move to opposite sides of the cell
What is the fifth step in mitosis?
The fifth stage is telophase, the phase in which the spindle begins to break down, the cell begins to elongate, and nuclear membranes form around each set of chromosomes
What is the sixth step in mitosis?
The sixth stage is cytokinesis, the stage in which the cell splits into 2 daughter cells. The organelles later reform
What is a chromatid?
A copy of a chromosome
What are stem cells?
Stem cells are types of cells that can differentiate into any other type of cell
What are the 2 types of stem cell?
Embryonic stem cells and adult stem cells. Embryonic stem cells are totipotent and can turn into anything. Adult stem cells are only found in certain parts of the body (e.g. bone marrow) and can only specialise into cells found in that area
How can embryonic stem cells be collected?
They can be found in the waste in the left over umbilical cord after the mother has given birth, or in the fertilised eggs that were not selected to be put into the womb in IVF
What is environmental variation?
Differences in plants due to the environment in which they live
What is a clone?
An organism produced asexually that has the same genetic material as its only parent
What can stem cells be used for?
Regrowing parts of the spinal cord, treating diabetes, repairing organs, replacing cells in the eye
Describe stem cells in plants
They are found in the meristem, and they are always totipotent
How are plants cloned?
A cutting is taken from the plant, before being placed into rooting power, which contains hormones that allow the plant to quickly grow
How can you remember the stages of mitosis?
Inter, Pro, Prometa, Meta, Ana, Telo, Cytokinesis
What are totipotent stem cells?
Stem cells that can differentiate into any other type of cell
What are the gametes in plants?
Pollen, ovule
What is the purpose of mitosis?
Without mitosis, we wouldn’t grow in the womb or regenerate dead cells as an adult
Why must gametes be haploid?
They will be combining with another gamete
Name some examples of regeneration in animals
Starfish can grow back limbs, lizards can grow back tails
