Cellular Transport And The Cell Cycle Chapter 8

Cellular Transport Cellular transport~ the “highway”of the cell. How substances move from one place to another throughout cells. Osmosis~ net movement of a solvent (H 2 O) through a selectively permeable membrane. Selectively permeable membrane~ a cell membrane that has control over what can enter and exit the cell.

Isotonic Solution Concentration level of the substance outside = concentration level of substances within the cell Allows Red Blood Cells to maintain shape. water in or out of cell at the same rate.

Hypertonic solution Concentration of the substance outside the cell is higher than the concentration inside the cell. Cell shrivels Water moves out of a cell

Hypotonic solution Concentration level of substance outside the cell < concentration level of substances within the cell. Cells burst if hypotonic Water moves into a cell

Cell Transport… Passive transport~ solvent moves from high to low across concentration gradient under its own power, passive transport is a form of diffusion. NO ENERGY USED Forms of passive transport include facilitated diffusion, diffusion, osmosis. Water, lipids (fats) and lipid soluble substances are some compounds that can be diffused through the plasma membrane by diffusion.

Cell Transport … Facilitated diffusion – Cell exerts no energy o Proteins help to move substances through plasma membrane. ( figure 8-5) o The most common solvents moved by F.D. are sugars and amino acids. F.D. uses the concentration gradient. Proteins provide needed paths and openings to allow particles to pass through.

Cell transport… Active transport- The cell exerts all the energy to produce the transport. And move it across its concentration gradient In order for active transport to occur a special transport protein called a carrier protein must attach to a particle from the substance. (figure 8-6) Active transport allows movement into and out of the cell, against the concentration gradient.

Cell transport… Endocytosis ~ engulfs materials and than moves them into cell for processing. Material doesn’t pass directly through membrane. Exocytosis ~ removes waste by merging with cells and kicking waste out to extra cellular fluid. (Figure 8.7)8.78-7)8.78-7)

Cell Growth and Reproduction. Cell size is influenced by: 1. Diffusion affects cell size because as the cell is larger it takes longer for the process to be finished. 2. DNA affects cell size because some cells have an increased amount of cytoplasm 3. SA-VR affects the cell size because a cells volume increases faster than the surface area.

Cell Reproduction… Cell reproduction occurs from a pre- existing cell.The Process that this occurs is cell division. Cell division results in two cells that are identical to the original cell. The most prevalent cells to regenerate are skin cells. All worn tissue gets replaced with new cells or repaired. ( pg.209)

Cell Growth and Reproduction The cell cycle is the sequence of growth and division of a cell. The cell goes through two general phases, growth and division. Interphase~ longest phase,a cell grows in size and carries out metabolism, also this is when chromosomes (DNA material) are duplicated. Mitosis is the phase following interphase. During mitosis two daughter cells are formed, each having all of its chromosomes, these two phases are the main phases of the cell cycle.

Why do cells divide by Mitosis ? Growth &Repair Reproduction of single celled organisms constant environment Amobea Reproducing

Cells dividing by Mitosis……. Identical to original cell Same chromosome # Identical chromosome makeup Skin

Cell Cycle 24 hours “G” or Growth 1 phase “S” or DNA Synthesis Growth 2 “M” or Mitosis phase //////

Where is DNA located ? 1. Nucleus 2. Chromosomes DNA

Duplicated Chromosome (Late Interphase): Sister Chromatids Centromere

Spindle & spindle fibers: Pull apart the sister chromatids Spindle fibers

Interphase Intermission Normal metabolic activities Major state DNA= chromatin

Late Interphase Prepares for mitosis DNA doubles= Sister chromatids Centrioles double in animals

Stages of Mitotic Cell Division Prophase Metaphase Anaphase Telophase “ 1st” “middle” “apart” “far” or separate

Prophase Nuclear membrane disappears Doubled DNA = condensed “chromosomes” Spindle fibers

Metaphase Chrom- osomes line up mid- cell Facing inward

Anaphase Chromosomes move to opposite poles at Centrioles in animals Spindle apparatus in plants

Telophase Cells divide Chromosomes unwind Cell plate or membranes form Nucleus reappears

Animal Telophase Interphase

Returns to Interphase “Intermission” Normal metabolic activities Major state DNA=chromatin

Plant versus Animal Mitosis Plant: Cell wall form cell plate in telophase Spindles Animal: No cell wall membrane cytokinesis Centrioles

Cell Growth and Reproduction… Cytokinesis- process in which cytoplasm divides. I- Interphase P- Prophase M- Mitosis A- Anaphase T- Telephase a good way to remember the phases of cell cycle is CIPMAT.ICIPPMAT.ICIPPMAT.

Control of Cell Cycle Enzymes control the cell cycle. Certain enzymes are important to begin and keep the cell cycle going, while certain enzymes only control certain phases. Cancer is the result of uncontrolled cell division. During uncontrolled cell division certain enzymes are not present or were not produced or environmental changes. Enzymes are directed by genes located on chromosomes.

Cancerous cells ……... 1.Divide too many times 2.Divide into more than two cells! Masses of cells = “tumors” benign malignant

Mitosis Flip Book Make two index cards for each phase of mitosis – ex. Early and late prophase, early and late metaphase etc…. Color and Label each part of the cell: Chromatin, sister chromatids, centromere, spindle, cell membrane Make one index card for interphase Describe each phase on the back of each index card