3 Flashcards
What are the 3 functions of cell division?
- Reproduction: usually refers to single-celled organisms that reproduce asexually)
- Growth, renewal, repair- ( usually refers to multicellular organisms)
- Maintenance of an adequate surface area-to-volume ratio
asexual reproduction
Asexual: reproduction by binary fission or mitosis. Only on organism/cell involved that divides into two .daughter cells are identical.
Sexual reproduction
Sexual: reproduction throught the fusion of male and female gametes/sex cells. Gametes are produced furing meiosis. Two organisms are involved. The offspring produced via sexual reproduction are genetically different than either of the parents. This allows genetic diversity among the offspring.
DNA
the genetic material ( deoxyribonucleic acid)
Chromatin
A loosely arranged form of DNA seen when a cell is not actively dividing
Chromosome
A tightly condensed form of DNA seen when a cell is actively dividing. ( 1 chromosome= one molecule of DNA)
Chromatid
One half of a duplicated chromosome
Centromere
Constricted region made of DNA that holds two sister chromatids together before they separate;also, the intended or constricted region on a chromsome; sometimes the centromere is located toward the middle of the chromosome, sometimes it is off center, and sometimes it is more toward the end. The location of the centromere is one way that chromosomes can be identified.
Histones
little protein spools that help organize DNA
Nucleosomes
histone proteins with two wraps of DNA on them. These are important in organizing DNA because this is how the DNA strand is condensed. ( This is how approx. six-feet of DNA can be compacted into the nucleus of a single cell.
how many chromosomes do humans have?
46
Does the amount of chromosomes relate to the size or complexity of an organism?
no.
define mitosis. Where does it occur in the body?
ordinary nuclear division for growth and repair; the chromosome number remains constant; occurs in body (somatic) cells
Define cytokinesis
division of the cytoplasm and its contents
What is a cleavage furrow?
in animal cells, forms when the cell invaginates all the way around and pinches itself into two daughter cells.
What is a cell plate?
In plant cells, it forms to divide the parent cell intwo two daughter cells.
mitosis
the ordinary nuclear/cell division for growth, repair and replacement of old worn out cells.
Describe the process of mitosis?
see drawing on back of review paper.
How many daughter cells are produces, and are they identical?
produces 2 daughter cells, they are identical to their parents and eachother.
What causes a cell to continue to divide or prevent it from doing so?
1) Outside influences, such as hormone’s or growth factors
2) Adhesion to a solid Surface- The cytoskeleton of cells has to have a solid surface to push against in order to divide
3) Contract inhibition- Normally, when neighboring cells touch each other, they stop dividing.
how is cancer related to mitosis?
Cancer is uncontrolled cell division ( mitosis). Cancer cells do not grow and divide faster than normal cells. The problem is that they do not stop growing, dividing or moving on contact. Cancer cells crawl over other cells, invade healthy tissues, and multiply into masses called tumors.
Metastasis
The spread of cancer cells from their site of origin to other parts of the body.
Benign tumor
-noncancerous
- cells remain differentiated
-encapsulated
-uniform shape
malignant tumor
-cancerous
-cells are undifferentiated
-not encapsulated
- not uniform in shape, can have “feelers”
- cna, and often do, spread/ metastasize
-life threatening