biology cell reproduction mitosis meiosis
Cell Reproduction Unit of Biology
Why do cells reproduce (divide)?
Demand on DNA, substances can't diffuse into cells with large volume as quickly as smaller cells.
How Bacteria reproduce. DNA copies and then the cell splits in two.
How to eukaryotic body cells reproduce?
DNA that is loose and uncoiled when a cell is not dividing.
DNA that is tightly coiled just before cell division
Each half of a copied chromosome (each half of the X)
Point where sister chromatids attach.
How do you count the number of chromosomes in an organism?
If there are 6 chromosomes in a cell and the DNA has copied, how many chromatids are there?
What are the phases of the cell cycle?
G1, S, G2, Mitosis, Cytokinesis
The longest phase of the cell cycle. Includes G1, S, and G2.
A cell in this stage is no longer dividing.
Gap 0 (G0)
Period of growth before division
Gap 1 (G1)
DNA replicates during this stage of the cell cycle.
Second period of growth during the cell cycle.
Gap 2 (G2)
Division of the nucleus.
Divison of the cytoplasm
Fibers that help move the chromosomes around by attaching at the centromeres.
Only in animal cells, the spindle fibers extend from these to attach to the chromosomes.
What is the goal of mitosis?
To creat identical cells. Creates somatic cells.
What are the phases of mitosis?
Prophase, Metaphase, Anaphase, Telophase
Phase of mitosis in which nuclear envelope breaks down, centrioles separate and spindle fibers form. Chromosomes are visible.
Phase in mitosis in which chromosomes line up in the middle (at the equator).
Phase in mitosis in which sister chromatids separate and are pulles to opposite poles (sides of the cell).
Phase of mitosis in which chromosomes begin to become chromatin. 2 nuclear envelopes reform around chromosomes. Spindle fibers break down.
How is cytokinesis different in plants and animals?
In plants a cell plate forms beftween the two cells and the cell wall forms on either side of the plate. In animal cells a cleavage furrow forms and the cell divides.
A mutation in the DNA that controls the cell cycle. The result are cells growing out of control.
How is the cell cycle controlled?
There are checkpoints to make sure the steps of the cell cycle have properly occured.
A tumor that does not spread or invade other parts of the body.
A tumor that invades surrounding tissues and can spread to other areas of the body.
Cancer that has spread
Body cels (hair, skin, and muscle cells)
Haploid sex cells (egg and sperm)
What is the goal of meiosis?
To creat sex cells with half the number of chromosomes.
Chromosomes similar in size, shape and genetic information. One comes from mom and one comes from dad.
2 sets of chromosomes
1 set of chromosomes
What is the diploid number of chromosomes in humans?
What is the haploid number of chomromosomes in humans?
Diploid fertilized egg
Chomromosomes not involved in determining sex.
Chromosomes that determine sex.
How many autosomes are in a human somatic cell?
44 (22 pairs)
How many sex chromosomes are in a human somatic cell?
2 (1 pair)
How many autosomes are there in a human gamete?
How many sex chromomes are in a human gamete?
What are the sex chromosomes for a human female?
What are the sex chromosomes for a human male?
Phase of meiosis in which chromosomes form tetrads, crossing over occurs, nuclear envelope breaks down, and spindle fibers form.
Phase in meiosis in which homologous chromosomes line up double file in the middle at the equator
Phase of meiosis in which homologous chromosomes are pulled apart to opposite poles
Phase in meiosos in which nuclear envelope reforms, cell divides into 2 cells, chromosome number is now cut in half.
Phase of meiosis in which nuclear envelope breaks down and spindle fibers form. Occurrs in 2 cells.
Phase in meiosis in which chromosomes line up single file in the middle of the cell at the equator.
Phase of meiosis in which sister chromatids separate to opposite poles.
Phase of meiosis in which chromosomes uncoil into chromatin, the nuclear envelope reforms and the 2 cells split into 4
Structure that forms when homologous chromosomes pair up (XX or xx)
Occurs during Prophase I. Homologous chromosomes exhange pieces of DNA
Random organization of the chromosomes at the equator
Where does meiosis occur in humans?
Testes and ovaries
Formation of sperm by meiosis
Formation of eggs by meiosis
A mutation in which a piece of chromosome breaks off.
Mutation that occurs during crossing over and instead of exchanging pieces equally, one chromosome has a section delted and this section is added to the homologous chromosome.
Duplication deletion mutation.
Mutation in which a chromosome piece reattaches to original chromosome but in reverse orientation.
Mutation in which a chromome piece attaches itself to a nonhomologous chromosome
Proper separation of chromosomes during meiosis
Failure of chromosomes to separate during meiosis resulting in too many or too few chromosomes in the gametes.
Picture of the chromosome in a cell that is used to check for abnormalities.
How does a person get too many or too few copies of a chromosome?
Humans with 3 copies of one chromosome
In which cells does mitosis occur?
Somatic cells (body cells)
What type of cells are formed during meiosis?
Gametes (sex cells)
Is mitosis involved in sexual or asexual reproduction?
Is meiosis involved in sexual or asexual reproduction?
how many times does the nucleus divide in mitosis?
How many times does the nucleus divide in meiosis?
Are the cells diploid or haploid at the beginning of mitosis?
Are the cells diploid or haploid at the beginning of meiosis?
Are the cells diploid or haploid at the end of mitosis?
Are the cells diploid or haploid at the end of meiosis?
What are the advantages of mitosis?
Quick process and little energy needed
What are the advantages of meiosis?
What are the disadvantages of mitosis?
No genetic diversity
What are the disadvantages of meiosis?
Takes time and energy
How many cells are produces at the end of mitosis?
How many cells are produced at the end of meiosis?
How are sister chromatids related?
They contain identical copies of DNA