Exchange with the Environment 4 -1

1. Exchange with the Environment 4-1 Every cell has a cell membrane! ~ protects ~ helps move things in and out of cell ~ cell memb. controls this by being selectively permeable - only lets certain things in/out ~ is made of lipids (fats) and has proteins in it to allow things in or out 2 types of transport: 1.) Passive transport - does not use energy *all things want to reach and be in equilibrium - when a space is filled evenly ex: Diffusion – movement of particles from areas of high concentration to low concentration Ex: Let's see it in action! http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html 2.) Active Transport - uses energy We will talk more about this in a bit...

2. Osmosis – movement ofwateracross a selectively permeable membrane in response to a high solute concentration Ex: Let's see it in action! http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html 3 conditions of osmosis: Hypertonic solution: more particles outside the cell than inside Solution is hypertonic Cell solution is hypotonic Water moves out of the cell Cell will shrivel and shrink Hypotonic solution: more particles inside the cell than outside Solution is hypotonic Cell solution is hypertonic Water moves into the cell Cell will burst! Isotonic solution: same solute concentration inside and outside the cell Solution is Isotonic Cell solution is Isotonic Water moves equally into and out of the cell Cell will stay the same solute particle water molecule

3. 2.) Active Transport - uses energy Vesicles: some substances are too large to go through the membrane Are brought in or released by these processes... ~ Endocytosis - cell engulfs or "eats" a substance Let's see how it works! ~ Exocytosis - cell releases a substance out of the cell * hormones, proteins http://www.college-cram.com/study/biology/cell-membranes/endocytosis/ Let's see how it works! http://www.college-cram.com/study/biology/cell-membranes/exocytosis/

4. Cell Energy! 4-2 Photosynthesis is how plants obtain energy! ~ done by autotrophs Plants take CO2 and H2O and convert it to glucose and O2. The heterotrophs then take those products (glucose and O2) and use them for energy in cellular respiration Ex: chloroplast photosynthesis O2 + glucose CO2 + H2O cellular respiration ATP mitochondria

5. 3 steps: 1.) Plants harvest energy from the sun ~ thylakoids – contain chlorophyll - within the chloroplast Ex: Chlorophyll is a pigment that absorbs red and blue but reflects green and yellow Also have carotenoids – absorb green and blue reflect red, orange and yellow ~ where we get the fall leaf colors!

6. 2.) Light reactions produce energy ~ uses light energy to make some ATP http://www.science.smith.edu/departments/Biology/Bio231/ltrxn.html 3.) Dark reaction produces sugars ~ "Dark" because it doesn't use light!! ~ use the ATP from the light reaction to make glucose!

7. Cellular Respiration Energy that was made in photosynthesis can be used in cellular respiration Has 2 stages: 1.Glucose converted to pyruvate - produces small amount of ATP *occurs in the cytosol 2. O2 present = pyruvate used to produce lots of ATP : aerobic - needs O2 * occurs in mitochondria (eukaryotic cells); * in cell membrane in cells w/o mitochondria O2not present = pyruvate converted to lactic acid or ethyl alcohol ~ anaerobic - w/o O2 Here's how it works: glucose ATP Aerobic Anaerobic pyruvate ATP O2 available ethyl alcohol or lactic acid O2 NOT available mitochondria

8. Connection between Photosynthesis and Cell Respiration These are the chemical equations for both processes...notice anything? Cell Resp.: C6H12O6 + O2 CO2 + H2O + 36ATP Photosynthesis Light + CO2 + H2O C6H12O6 + O2 One cannot be without the other! They form a continuous cycle!

9. Without O2, Fermentation occurs!(Just write and know the things in color!) *instead of the e- getting carried away by NAD+, the e- remain attached to NADH *this takes up all available NAD+ and then glycolysis can't continue *SO the H+ must be attached to something else… - in animals = H+ gets attached back to pyruvate to form ... lactic acid *this is what causes your muscles to hurt when you work out! - in plants = H+ gets attached to CO2 from glycolysis to form ... ethyl alcohol *this is what causes bread to rise (CO2) and beer to become alcoholic (ethyl alcohol) *Yeast is the microorganism that performs this task!

10. The Cell Cycle 4-3 Chromosomes! Chromosome - rod shaped structure that forms when a single DNA molecule and its associated proteins coil tightly before cell division *Made up of genes which make up DNA - ~ segment of DNA that carries info from the parent to the offspring *Usually the DNA strand is uncoiled when in use. *When the cell prepares to divide, the DNA coils up and compacts for easier division DNA looks like this:

11. Chromatid - one of a pair of strands of DNA that make up a chromosome *DNA replicates itself before cell division so each new cell will have the same genes The chromatids are joined in the center by a centromere made of protein. chromatid chromatid They look like this: centromere chromosome

12. We have 23 types of chromosomes! (46 total) *body cells have 2 of each type of chromosome (diploid) *the 2 copies of each type are homologous chromosomes *one copy from Dad, one from Mom Homologous *sex cells (gametes) only have 1 of each type (haploid) When 2 sex cells join, then the new zygote will have the correct number of chromosomes!

13. FYI: Chromosomes affect development: *Most babies with less than 46 die before they become a fetus. * A person can live with more…like 47: ~ Down Syndrome = has extra chrom. #21 ~ trisomy – extra chromosome in a 2n cell ~ can determine this with a karyotype – look at a map of the chromosomes… Chrom. # 21 does not separate at time of cell replication = nondisjunction ie: one cell gets both chrom’s and the other gets none. Mutations – changes in an organism’s genetic material Sex chromosomes are the only pair the determine whether you’re female or male! 2 forms = X and Y The presence or absence of the Y chromosome is what determines the sex… this is because the hormone that makes a male is located on the Y ·Without it, the organism is female! With us… Females = XX Males = XY

14. Mitosis and the Cell Cycle 4-3 Your book says the cell cycle is in 3 stages: 1 - Interphase 2 - Mitosis 3- Cytokinesis Let's see how it works! http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html (Interphase can be broken into 3 phases and Mitosis is really 4 so just FYI ...there are phases within these phases!) Interphase: ~ this phase is what the cell spends most of its life in * During this phase the DNA is copied , at end you have a chromosome with 2 chromatids * When interphase ends, Mitosis now begins (M phase) Here’s what takes place now…

15. Mitosis! Prophase: * chrom. begin to condense * enzymes break down nuclear envelope * cylindrical centrioles start to separate and move to opposite ends of the cell – called “polar bodies” * protein fibers from centriole form spindle fibers – made of microtubules **NOTE! Plants do NOT have centrioles!**

16. Metaphase: * chrom. keep condensing * chrom. line up in the center of the cell – “equator” * more microtubules extend out of the centromere at the kinetochore – hold the chroms in place * one chromatid is attached to one centriole, one to the other

17. Anaphase: * centromere divides and the 2 chromatids separate * the new chroms. move to opposite sides as the spindle fibers shorten

18. Telophase: * chroms uncoil at either end of cell *new nuclear envelope forms * spindle fibers break down and disappear

19. Cytokinesis begins – cell is cleaved in half * cell membrane grows to close both * done by a belt of protein threads In plants… golgi bodies form a cell plate at the center of the cell to build a new cell wall - once the wall is complete, the cell separates!

20. SO... The whole Mitosis process is like this: Let's see it in action! http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html