Chapter 10 and 11.4 Biology

Describe why cells divide instead of growing larger

the demand of DNA becomes too small for the big cell and it gets hard to move things in and out of it.

Describe how internal regulators (cyclin) and external regulators work to control the cell cycle

they work to control the cell cycle by using cyclins to regulate the cycle and checkpoints to keep everything in line (internal) and lack of space and growth factor (external)

Define mitosis and cytokinesis

Cytokinesis is the physical process of cell division, which divides the cytoplasm of a parental cell into two daughter cells. It occurs concurrently with two types of nuclear division called mitosis and meiosis (M phase)

Describe the end result of meiosis

male meiosis- four sperm cells are formed female meiosis- one egg and three polar bodies are created (polar bodies get destroyed)

Define meiosis and explain why we need it to occur

meiosis is the making of sex cells and we need it to occur in order to reproduce.

Describe the process of apoptosis

the cell kills itself and it's nutrients go to needed places.

Distinguish between diploid cells and haploid cells

the difference between the two is the number of chromosomes in the nucleus- diploid has 46 haploid has 23

M phase (mitosis and cytokinesis)

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

Define homologous chromosomes

A homologous chromosome is an individual mom or dad chromosome that puts together to make a pair

Describe sexual and asexual reproduction and discuss the advantages and disadvantages of each type of reproduction

Asexual reproduction generates offspring that are genetically identical to a single parent. In sexual reproduction, two parents contribute genetic information to produce unique offspring. Disadvantages are asexual has no genetic variation and sexual you have to find a mate/takes a long time. Advantages of asexual are its faster and you don't need a mate and sexual has genetic variety.

Interphase (G1, S, G2)

Cell Growth, Reproduction, Preparation for mitosis

Describe the events of the cell cycle

Cell cycle, the ordered sequence of events that occur in a cell in preparation for cell division. The cell cycle is a four-stage process in which the cell increases in size (gap 1, or G1, stage), copies its DNA (synthesis, or S, stage), prepares to divide (gap 2, or G2, stage), and divides (mitosis, or M, stage).

Describe the checkpoints in the cell cycle and identify where they occur

G1, G2, Metaphase

Describe what happens in Meiosis I and Meiosis II

In Meiosis I the DNA is replicated; crossing over occurs in tetrads; homologous pairs split in Meiosis II no DNA replication; sister chromatids separate; final haploids are created

Describe the unique events of prophase 1

In meiosis tetrads are formed and they cross over dna where in mitosis they don't do that.

Describe the difference between cytokinesis in plants and animals

In plants a new cell wall is fashioned between the new daughter cells, while in animal cells the cell membrane constricts to pinch the parent cell into daughter cells.

Describe the role of the centrioles and the spindle

Long protein fibers called microtubules extend from the centrioles in all possible directions, forming what is called a spindle. these spindles come out of the centrioles and attach to the centromere of the chromosomes, then pull them into two

Describe what happens at each phase of the cell cycle

Meiosis I is where prior to the whole cycle the cell replicates during interphase. Then in Prophase I the cell begins to divide and the chromosome pair up. Each replicated chromosome pairs with its corresponding homologous chromosome forming the tetrad contains four chromatids. They undergo a process called crossing over where the chromatids cross from one homologous chromosome to another. After in Metaphase I and Anaphase I the spindle forms and attaches to each tetrad. During metaphase I The homologous chromosomes line up across the center of the cell. This moving to Anaphase I were the homologous pairs separate and the spindle fibers pull each chromosome pair towards opposite ends of the cell. Finally in Telophase I and Cytokinesis the separate chromosomes cluster at opposite ends of the cell and during telophase I a nuclear membrane forms around them before cytokinesis forms two new cells.

Describe the difference between chromosomes in prokaryotes and eukaryotes

Prokaryotes have free floating DNA and Eukaryotes have a nucleus where the DNA is enclosed.

Describe the relationship between chromatin, chromosomes, sister chromatids, and centromeres

chromotin is compacted chromosomes which are made of sister chromatids that are connected in the centromere.

Describe a tetrad and crossing over

The tetrad occurs during the first phase of meiosis. It is the foursome of chromatids that forms when replicated homologous chromosomes align. It must be formed for crossing over to occur. Crossing over is the sharing of DNA between homolegous chromosomes.

Describe what happens when a cell cannot control its rate of division

When it can't control the rate of division it just keeps going - this is how tumors are formed.