CELL GROWTH AND REPRODUCTION

10.1 / 10.2 Cell Growth and Reproduction Cell Size Limitations DIFFUSION limits cell size. Diffusion is a fast efficient process over short distances, but becomes slow and inefficient as the distance becomes larger DNA limits cell size. DNA controls the production of proteins in the cytoplasm INCREASE in cell size → DECREASE in protein production.

3. Surface area-to-volume ratio Each time a cell DOUBLES in size, its surface area increases by a factor of 4, but its volume increases by a factor of 8. Therefore, the cell would need 8 times the normal amount of nutrients, and would have 8 times the normal amount of wastes to excrete.

Cell Reproduction CELL REPRODUCTION results in 2 cells that are identical to the original parent cell. CHROMOSOMES- the carriers of genetic material (DNA that is copied and passed from generation to generation of cells) CHROMATIN- long strands of DNA wrapped around proteins Before a cell can divide, the long strands of chromatin must be reorganized; they become tightly packed.

The Cell Cycle The cell cycle is the sequence of growth and division of a cell. The cell goes through 2 general periods

INTERPHASE

G1- interphase begins with this stage 1. INTERPHASE- the growth period in which the majority of a cell’s life happens. G1- interphase begins with this stage a. Protein synthesis is rapidly occurring as cell grows and develops. S – second stage of interphase Chromosomes are replicated in the nucleus. Chromosomes divide to form identical sister chromatids connected by a centromere. G2- final stage of interphase Chromosomes begin to shorten and coil Protein synthesis is in high gear Cell organizes and prepares for division

PROPHASE – first and longest phase of mitosis 2. MITOSIS – period of nuclear division by which two daughter cells are formed. PROPHASE – first and longest phase of mitosis Chromatin coils up into visible chromosomes SISTER CHROMATIDS – the 2 halves of a duplicated chromosome CENTROMERE – holds sister chromatids together Nucleus begins to disappear CENTRIOLES migrate to opposite ends o the cell SPINDLE begins to form between them

PROPHASE

METAPHASE – short second phase of mitosis Chromosomes become attached to the spindle fibers by centromeres. Chromosomes are pulled by the spindle fibers and line up in the middle, or equator of the cell.

ANAPHASE – the third stage of mitosis Separation of sister chromatids

TELOPHASE – the final stage of mitosis a. chromatids reach opposite ends of a cell b. chromosomes uncoil, nucleolus and nuclear envelope reappear.

CYTOKINESIS IN ANIMALS

CYTOKINESIS IN PLANTS

Cell Division Assignment As your read in your text/notes about cell reproduction, arrange the drawings in sequence, so that the illustrations represent the correct order of the phases of mitosis: Prophase, Metaphase, Anaphase, Telophase (PMAT) Cut out the 4 labels. Place the drawings in the correct order have Ms. Williams check them. Glue the cell drawings in a cycle on paper so that you have a poster of mitosis. Glue each label “near” the correct illustration(s) for the name of the phase. Label the following structures everywhere applicable (DNA, centrioles, spindle fibers, centromere, cell equator, nuclear membrane, plasma membrane, nucleolus, cytoplasm, cleavage furrow, cell plate)

Cell Division Assignment For each phase of mitosis (P-M-A-T) please provide A suitable definition Appropriately cut and paste the key events characteristic of each phase. Choose 1 event for each phase of mitosis and explain its importance/significance to the next phase of the process?

RAFT ASSIGNMENT MITOSIS Objective: Create a nonfiction writing assignment using the key concepts of mitosis Introduction-What is RAFT? Role of the writer. What is the writer’s role: reporter, observer, eyewitness, etc? Audience. Who will be reading this writing: the teacher, other students, a parent, people in the community, etc. Format. What is the best way to present this writing: a letter, an article, a report, a poem? Topic. Who or what is the subject of this writing:

“What I leave you when I die” “Why are you copying me?!?” Directions: Start by choosing the role from which you will write. Use the table to discover the rest of the assignment. You may choose any of the 3 combinations. Role Audience Format Topic 1. Parent Cell Daughter Cell Will “What I leave you when I die” 2. Skin Cell Skin Cell Letter to Editor “Why are you copying me?!?” 3. Chromosome Nucleus Text Message “Why I am important!”