CHAPTER 8 Flashcards
what are the three functions of mitosis? give examples.
- Growth
- Replace damaged cells
- Asexual reproduction
be able to draw parts of the chromosome (centromere, sister chromatids)
2 identical copies called sister chromatids (separate when the cell divides) are attached by a centromere
know all parts of the eukaryotic cell cycle
- Interphase
-G1 = growth, cellular respiration
-S phase = where chromosomes are copied
-G2 = growth and cellular respiration - Mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
- Cytokinesis
describe the 4 phases of mitosis in plant and animal cells. (be able to recognize in a diagram)
- Prophase → chromosomes coil up (they become visible); the nuclear envelope briefly breaks up; spindle apparatus starts to form with 2 centrosome → which make up spindle fibers
- Metaphase → chromosomes line up single file one way along another of the center of a cell
- Anaphase → sister chromatids separate
- Telophase & Cytokinesis → reverse of prophase (chromosome uncoils, nuclear envelope reforms, spindle disappears); division of the cytoplasm with all the organelles divided in half
-In an animal cell: Cleavage furrow forms → pinches 2 daughter cells in half
-In a plant cell: Cell plate forms
what is cancer?
- disease of cell cycle
- the result of uncontrolled mitosis
- cells divide repeatedly out of control because the oncogenes responsible for switching on and off cell division malfunction
-cells form an irregular mass of cells called a tumor
define benign and malignant tumors.
benign - if the tumor stays at the original site
malignant - if tumor spread to other tissues (cancer)
identify traits of cancer cells
- immortal
-they migrate easily to other tissues of the body - don’t stay in monolayer -> forms a “mass”
identify cancer treatments (4 types)
- slash it with surgery
- burn it with radiation
- poison it with chemotherapy
- “starve” the tumor -> cut off the blood supply => starve it of Oxygen and nutrients
identify prevention
- no smoking = may cause 30%-60% of cancers
- healthy diet => more fiber, less fats (~30% of cancers)
- regular exercise
- less stress + dealing with it
- if family history => get screened
define meiosis and where it occurs in the human body
-basis of sexual reproduction to make gametes (egg or sperm cells) → that are all genetically unique
-Only occurs in the sex organs → ovaries (female) or testes (males)
know the number of chromosomes in humans. (in somatic cells and gametes)
somatic cells: 46
gametes: 23
describe the human life cycle (be able to diagram)
In ovaries there are eggs and in testes there are sperm which are haploid gametes with meiosis, the sperm finds the egg and fertilizes it turning it into a zygote which is a diploid cell
define karyotype
human diploid cell
define homologous chromosomes
matching pair of chromosomes; one from each parent and they may carry different versions of the same genes (meaning one might be dominant one might be recessive)
describe all phases of meiosis I (be able to recognize diagram)
-Prophase 1 → chromosomes coil up, nuclear envelope breaks apart, spindle apparatus starts to form, the homologous chromosomes pair up (one from the father one from the mother), crossing over occurs (where they touch they swap genes *random process) 1st source of genetic variation
-Metaphase 1 → homologous pair of chromosomes line up independently from each other → independent assortment; 2nd source of genetic variation
-Anaphase 1 → Homologous pairs separate
-Telophase 1 → Chromosomes uncoil, Nuclear envelope reform, Spindle goes away , End up with two haploid cells (cytokinesis)
describe all phases of meiosis II (be able to recognize diagram)
Prophase 2 →Chromosomes coil up, Nuclear envelope breaks apart, Spindle apparatus starts to form
Metaphase 2 →chromosomes line up single file one way along another of the center of a cell
Anaphase 2 →Sister chromatids separate
Telophase 2 →(at the same time cytokinesis is happening) → reverse of prophase (chromosome uncoils, nuclear envelope reforms, spindle disappears)
Cytokinesis → division of the cytoplasm with all the organelles divided in half; Cleavage furrow forms → pinches 2 daughter cells in half
why is genetic variety in offsprings important?
-It allows some of the offspring to survive from severe diseases or environmental changes
-Bc without it evolution cannot happen
what events in prophase I and metaphase I of meiosis I contribute to genetic variation? what is the third source?
-Prophase 1 -> (crossing over) Homologous chromosomes are pairing up when they touch bc they are sticky the swap genes and causes genetic shuffling
-Metaphase 1 ->Line up in homologous independant assortment
-Random fertilization: 2^23 in the egg X 2^23 in the sperm = 64 trillion chromosome variations
define and describe nondisjunction in meiosis. (give examples)
-When meiosis goes awry –> You can get abnormal number of chromosomes in your sperm and egg cells
-If these are the original egg or sperm every other gamete will have this abnormal number
-why? Due to nondisjunction: accidental failure of chromosomes to separate during anaphase 1 or 2
-ex: down syndrome: trisomy 21 (3 copies in chromosome #21), Abnormal number of sex chromosomes
