grade 9 science · grade 9 science chapter 5.notebook 4 january 10, 2014 dec 308:03 pm asexual...
TRANSCRIPT
Grade 9 Science Chapter 5.notebook
1
January 10, 2014
Dec 307:57 PM
Grade 9 Science
Unit 3: ReproductionChapter 5
Dec 308:03 PM
The Cell CycleThe cell cycle is the life cycle of a cell
There are three parts to the life cycle:1) Interphase: most of the cell's life is spent in interphase, in this stage, the cell carries out the functions they need to divide and prepare for reproduction ‐ these include growth, preparation, and DNA replication2) Mitosis: in this stage the cell duplicates the contents of the cells nucleus into two equal parts3) Cytokinesis: the cell separates the two nuclei and cell contents into two new daughter cells
Grade 9 Science Chapter 5.notebook
2
January 10, 2014
Dec 308:41 PM
Dec 308:03 PM
MitosisMitosis is the process in which the contents of a cell's nucleus divide, this results in two daughter cells that are identical to the parent
There are four phases of Mitosis (cytokinesis follows these 4) :1) Prophase: the double stranded chromosomes shorten and thicken; the nuclear membrane begins to fade2) Metaphase: X‐shaped chromosomes are pulled into a single line across the middle of the cell3) Anaphase: the chromatids are pulled to opposite poles of the cell4) Telophase: the nuclear membrane forms around each set of chromosomes; the cell is ready to divide into two separate cells
Animal cell Plant cell
Activity 51C
Grade 9 Science Chapter 5.notebook
3
January 10, 2014
Dec 308:48 PM
Checkpoints in the Cell Cycle
Proteins in the cell check the viability of the cell at certain points in the cell cycle. This information is directed to the nucleus, which decides whether or not the cell will divide.The cell will not divide if there are not enough nutrients to support growth, DNA has not been replicated, or the DNA has been damaged!
Dec 308:03 PM
Asexual ReproductionIn asexual reproduction, only one parent is involved and offspring are identical to the parent. Most reproduce quickly and in large numbers
There are five types of asexual reproduction:1) Binary Fission: a single parent cell replicates its genetic material and divides into two equal parts
Ex. Amoeba and Bacteria2) Budding: part of the cell pushes outward to form an outgrowth or bud, the bud pinches off to form the new offspring identical to the parent ‐ not all buds break away!!!
Ex. Yeast, Hydra, and sponges3) Fragmentation: an organism breaks apart as a result of injury, each fragment then develops into a clone of
its parentEx. Star‐fish and Japanese Knotweed
Grade 9 Science Chapter 5.notebook
4
January 10, 2014
Dec 308:03 PM
Asexual Reproduction Continued...Types of asexual reproduction continued:
4) Vegetative Reproduction: occurs when special cells, in plants and roots, divide repeatedly to form structures that will eventually develop into plants identical to the parent
Ex. Potato sprouts, Strawberry runners, and Tulip Bulbs
5) Spore Formation: a spore is a reproductive cell that grows into a new individual by mitosis, they are light in weight, rely on water, or wind to carry spores away from parent plant
Ex. Bread mould and puffballs
Dec 308:03 PM
Summary of Asexual Reproduction Advantages:
‐ Large # of offspring are produced quickly‐ Large colonies can form to out‐compete‐ Large # of offspring mean the species may survive when conditions change‐ Energy is not required to find a mate
Disadvantages:‐ Offspring are genetic clones, negative mutations can destroy larges numbers‐ The produced close together must compete‐ Unfavorable conditions can wipe out entire colonies
Bookwork: Questions 1, 2‐11 & 13on page 165
Grade 9 Science Chapter 5.notebook
5
January 10, 2014
Dec 308:29 PM
Core Lab Activity 5‐2B: Determining the Best Conditions for Yeast
Reproductions
Read the procedure on Pages 162‐164