Cell Cycle

meiosis

(genetics) cell division that produces reproductive cells in sexually reproducing organisms

8.15-8.17 Explain how independent orientation of chromosomes at metaphase I, random fertilization, and crossing over contribute to genetic variation in sexually reproducing organisms.

-Crossing over occurs during prophase I of meiosis I. It involves the switching of genes between the non-sister chromatids of homologs which allows the novel mixture of maternal and paternal genetic material with new, recombinant chromosomes. -Another layer of variation occurs during independent assortment which is the random lining up of the homologs during metaphase I of meiosis I. Between different gametes, there are 2n different possibilities of how the homologs could line up. -chromosome material and paternal chromosomes line up during. Finally, it is completely random which sperm fertilizes which egg which creates even more potential variation in the offspring.

cytokinesis

-division of the cytoplasm to form 2 new daughter cells -organelles are divided -daughter cells are genetically identical

8.7-8.8 Explain how cell density and chemical growth factors affect cell division.

An organism must be able to control the timing of cell division - Anchorage dependence • Most animal cells must be in contact with a solid surface to divide

8.14 Describe the similarities and differences between mitosis and meiosis. Explain how the result of meiosis differs from the result of mitosis.

Both mitosis and meiosis are associated with cytokinesis. The end result of both are daughter cells produced from a parent cell. The fundamental sequence of events in mitosis is the same as in meiosis (in meiosis it happens twice). Both processes include the breakdown of the nuclear membrane, the separation of the genetic material into two groups, followed by cell division and the reformation of the nuclear membrane in each cells. The processes differ in two fundamental. Meiosis has two rounds of genetic separation and cellular division while mitosis only has one of each. In meiosis homologous chromosomes separate leading to daughter cells that are not genetically identical. In mitosis the daughter cells are identical to the parent as well as to each other.

8.9 Explain how cancerous cells are different from healthy cells. Distinguish between benign and malignant tumors, and explain the strategies behind some common cancer treatments.

Cancerous cells divide non-stop, healthy only divide when needed to repair or grow. *Benign- NOT cancerous. DON'T spread. can be removed & usually don't come back. *Malignant- ARE cancerous. WILL spread. They will go out of control and CAN'T be removed.

hiploid

Having the same number of sets of chromosomes as a germ cell, or half the diploid number of a somatic cell. The haploid number 23 in humans

8.11 Describe the number and organization of human chromosomes in a typical somatic cell. Distinguish between autosomes and sex chromosomes.

Human chromosomes in a typical somatic cell 46 -Because they determine in individuals sex, the X and Y chromosomes are called sex chromosomes -Chromosomes other than sex chromosomes are called autosomes.

8.4 Describe the stages of the cell cycle. Identify when DNA is replicated, chromosomes are sorted, and two new cells are formed.

Interphase: duplication of cell contents (g1, s, g2) DNA REPLICATED Mitosis: -prophase/ -metaphase/ -anaphase/ CHROMOSOMES SORTED -telephone/ Cytokinesis: cytoplasm divides TWO NEW CELLS FORMED

8.5 List the phases of mitosis and describe the events characteristic of each phase. Recognize the phases of mitosis from diagrams and micrographs.

MITOSIS: Prophase- in the cytoplasm microtubles begin to emerge from centrosomes, forming spindle fibers, chromosomes coil and get tight, nuclei dissapears. Metaphase- spindle fibers fully formed, chromosomes align at cell equator, sister chromatids facing opposite poles of the cell. Anaphase-sister chromatids seperate the centrosomes; daughter chromosomes move to opposite poles. Telophase- cell gets bigger, nucleur envelope forms, spindle fibers dissapear

8.13 Explain why sexual reproduction requires meiosis.

Meiosis is the making of the gametes to be used in sexual reproduction.

8.13 List the phases of meiosis I and meiosis II and describe the events characteristic of each phase. Recognize the phases of meiosis from diagrams and micrographs.

PI-synapsis and crossing over, MI, AI- homologous pairs separate TI- starts cytokinesis- 2 haploid cells. NO DUPLICATION IN BETWEEN- meiosis II- same as mitosis in 2 cells from meI- TII starts cytokinesis- 4 haploid cells.

8.1 Explain why cell division is essential for prokaryotic and eukaryotic life.

Some cell division results in a whole new organism. Prokaryotic organisms like the yeast cell reproduce by dividing in half, making the offspring genetic replicas. Cell division enables sexually reproducing organisms to develop from a single cell. Cell division also repairs and replaces cells that die. Within your body, millions of cells must divide every second to replace damaged or lost cells.

8.6 Compare cytokinesis in animal and plant cells.

They both undergo division Animal- there is a cleavage furrow Plants- plate formation

sex chromosome

a chromosome involved with determining the sex of an organism, typically one of two kinds

gamete

a mature sexual reproductive cell having a single set of unpaired chromosomes

cell plate

a membrane-bound disc made from vesicles that join together during cytokinesis in a plant

cell cycle

a repeating sequence of growth and division during the life of a cell; a cycle of growth, development, and division that most cells in an organism go through

centromere

a structure that holds sister chromatids together

growth factor

a substance, such as a vitamin or a hormone, that is required for the stimulation of growth in living cells.

tumor

an abnormal new mass of tissue that serves no purpose

somatic cell

any cell of a living organism other than the reproductive cells

autosome

any chromosome that is not a sex chromosome

mitosis

cell division in which the nucleus divides into nuclei containing the same number of chromosomes

Anaphase

chromosomes split at the centromere and move to opposite poles

homologous chromosomes

chromosomes that are similar in size, shape, and kinds of genes they contain

diploid

containing two complete sets of chromosomes, one from each parent (46 in human cells)

cleavage

division

malignant tumor

harmful

benign tumor

harmless

sister chromatid

identical pairs of chromatids

cleavage furrow

is the indentation of the cell's surface that begins the progression of cleavage, by which animal and some algal cells undergo cytokinesis, the final splitting of the membrane, in the process of cell division.

8.3 Describe the formation, structure, and fate of sister chromatids.

joined copies of an original chromosome. Two sister chromatids are attached together along their lengths by proteins are cinched at the center (centromere). When the cell divides they separate

chromatin

long, thin strands of DNA when actively dividing cells make copies of their DNA

cell cycle control system

monitors and dictates the progression of the cell through the cell cycle.

cancer

occurs when you have uncontrolled growth and division of cells

metastasis

process by which cancer cells are spread by blood or lymph circulation to a distant organ

8.3 Compare the structure of prokaryotic and eukaryotic chromosomes.

prokaryotes do not have a nuclear membrane so it doesn't have to copy more stuff, but eukaryotes are more complex that have more genes on multiple chromosomes-Prokaryotes have one single strand of DNA 1 chromosome, Eukaryotes have multiple chromosomes

asexual reproduction

reproduction without the fusion of gametes

8.12 Distinguish between somatic cells and gametes and between diploid cells and haploid cells.

somatic has 46 (diploid) gametes has 23 (haploid)

chromosome

something that carries genetic information in our nucleous

cell division

the division of a cell into two daughter cells with the same genetic material.

mitotic phase (M phase)

the division of the mother cell into two daughter cells genetically identical to each other

nondisjunction

the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.

fertilization

the joining of a sperm cell and an egg cell

mitotic spindle

the macromolecular machine that segregates chromosomes to two daughter cells during mitosis

karyotype

the number and visual appearance of the chromosomes in the cell nuclei of an organism or species. (n)

sexual reproduction

the production of new living organisms by combining genetic information from two individuals of different types (sexes). In most higher organisms, one sex (male) produces a small motile gamete that travels to fuse with a larger stationary gamete produced by the other (female).

zygote

the single cell that is formed from the 2 gametes during fertilization

crossing over

when chromosomes exchange genetic material

8.18 Define nondisjunction, explain how it can occur, and describe what can result.

°Nondisjunction is either the failure of homologous chromosomes to separate properly during meiosis 1 or the failure of sister chromatids to separate during meiosis 2. °results in the zygote (fertilized egg) which may have TRISOMY (3N) of a single chromosome or MONOSOMY Classic case of trisomy is Down's syndrome (extra chromosome at chromosome 21)

interphase

°cell growth °dna replication occurs °preparation for mitosis °normal cell activites

telophase

°chromosomes disappear °nuclear membrane reforms °nucleoli reappears °spindle disappears °centrioles double

metaphase

°chromosomes line up in the center of the cell and spindle attaches

prophase

°chromosomes visible °centrioles migratee to pole °nuclear membrane and nucleous disappear °spindle forms