what happens in a cell during interphase?
DNA is duplicated within cell
why is it important for DNA to be duplicated before Mitosis?
The chromosomes wouldn't be identical or split evenly
Functions of single-celled organisms
They reproduce through the cell division
Functions of multicellular organisms
Cell division is involved in growth, development, repair, and reproduction
What would happen if the cell went the mitosis but not cytokinesis?
There would not be two different cells
Why do cells divide?
To reproduce; for growth and repair
Reproduction of cells
Important for asexual reproduction; involves one parent
Growth & Repair of cells
Used in multicellular organisms to make new cells and repair old ones
What does DNA stand for?
DeoxyriboNucleic Acid
What happens to DNA during cell division?
Molecule holds traits; instructions for growth, development, and activities
Chromatin
Mass of loose DNA strands during most of a cell's life cycle
Chromosomes
Visible structures of compacted chromatin as a cell division begins
How many chromosomes does a human being have?
46
Mitosis: Profase
The chromatin in the nucleus of a cell condenses and becomes visible under a microscope
Mitosis: Metaphase
Chromosomes line up in the middle of the cell
Mitosis: Anaphase
The chromatids separate; they are pulled to opposite sides of the cell.
Mitosis: Telophase
A new nuclear membrane forms around each group chromosomes
Cytokinesis
The cytoplasm divides and two new cells are produced
# of chromosomes in sex cells compared to # of chromosomes in body cells
Having the genetic info body cells have; when 2 sex cells combine, there will be one full set of genetic info
Meiosis
Produces haploid sex cells
# of chromosomes that a body cell have
46
Sex cells differing from body cells
Having half of the genetic info; is one full set of DNA when 2 sex cells combine
Homologous chromosomes
Paired; carry diff. Versions of same genes; about same size & structure; have 23 pairs in body cells
Sex chromosomes
Control development of sexual characteristics (x and Y chromosomes); contains diploids
Diploids
Cells that contain two pairs of chromosomes. (46) (Body cells)
sex cells (gametes)
Have half # of chromosomes (23); are haploid; made in the reproduction organs of plants & animals
haploids cells
Has one chromosome from each homologous pair; two haploids = 1 diploid (body cells)
Two parts of Meiosis:
Meiosis I & Meiosis II
Meiosis I:
Homologous chromosomes split into 2 new cells (chromatids are still joined)
Amoeba
A single-celled organism. Reproduces by dividing in two.
Meiosis II
Results w 4 haploid cells (4 sperm & 1 egg)
Different name for eggs in females
Ovanies
Different name for sperm in males
Testes
Which cells do NOT undergo mitosis?
sperm and egg cells
2 ways mitosis is important
Can repair; can help you grow
In mitosis, the cells that are created are . . .
Skin cells or stomach cells
What would occur if cells were in mitosis more than they were in interphase:
There would be too many cells and would cause cancer
What is a chromosome made of?
DNA and proteins
Mitosis starts and ends with which type of cells
Diploid
How may chromosomes should be in each diploid after mitosis?
46
# of chromosomes when a sperm and egg cell come together
46 together
What a would happen if interphase didn't occur first in the cell cycle?
It's the starting cell that contains 46 chromosomes; cell would not be able to be r�duction division
How many chromosomes does a cell have when starting meiosis?
23 from mother, 23 from father (46)
Crossing Over
Process in which homologous chromosomes exchange portions of their chromatids during meiosis.
PMAT
Prophase, Metaphase, Anaphase, Telophase
How do you know if something is METAPHASE 1 or METAPHASE II?
Metaphase 1 has chromosomes that are in pairs down middle. Metaphase II has chromosomes that make single line down middle
Nondisjunction
Error in meiosis in which the homologous chromosomes fail to separate properly
single celled organisms
Single celled reproduce through cell divisions
Multicellular Organism
Cell divisions are involved in growth, development, repair, and reproduction
End result of Mitosis
Two new identical sets of chromosomes in two separate nuclei
Organs that develop in sex cells in human males and females
Testes in males; ovaries in females
In meiosis, after there are two new sex cells, what do they turn into?
Male- sperm cells; female- egg cells
Centromere
Holds chromatids together
Sister Chromatids
2 identical copies of a chromatin connected by a centromere
Chromatids
Duplicated chromosome consisting of 2 identical structures