Exchange with the Environment

Transcription

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! how_diffusion_works.html 1

2 Osmosis movement of water across a selectively permeable membrane in response to a high solute concentration Ex: = Solute *particle in solution Let's see it in action! 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 solute particle water molecule 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 2

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 cram.com/study/biology/cell membranes/endocytosis/ cram.com/study/biology/cell membranes/exocytosis/ Let's see how it works! 3

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

5 3 steps of Photosynthesis: 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! 5

6 2.) Light reactions produce energy ~ uses light energy to make some ATP 3.) Dark reaction produces sugars ~ "Dark" because it doesn't use light!! ~ use the ATP from the light reaction to make glucose 6

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

8 Connection between Cell Respiration and Photosynthesis... These are the chemical equations for both processes...notice anything? Cell Resp: in mitchondria! C 6 H 12 O 6 + O 2 CO 2 + H 2 O + 36ATP Photosynthesis: in chloroplasts! Light + CO 2 + H 2 O C 6 H 12 O 6 + O 2 One cannot be without the other! They form a continuous cycle! 8

9 Without O 2, 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 continue ca *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 CO 2 from glycolysis to form... ethyl alcohol *this is what causes bread to rise (CO 2 ) and beer to become alcoholic (ethyl alcohol) *Yeast is the microorganism that performs this task! 9

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: 10

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. They look like this: chromatid chromatid centromere chromosome 11

12 we have 23 types of chromosomes! (46 total) *body cells have 2 of each type of chromosome Called: 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 of chromosome Called : haploid When 2 sex cells join, then the new zygote will have the correct number of chromosomes! Fertilization of egg by sperm Zygote 12

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: the chromosomes ~ Down Syndrome = has extra chrom. #21 ~ trisomy extra chromosome in a 2n cell ~ can determine this with a karyotype look at a map of 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 2 forms = X and Y female or male! 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 13

14 Mitosis and the Cell Cycle 4 3 Your book says the cell cycle is in 3 stages: 1 Interphase 2 Mitosis 3 Cytokinesis (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 Let's see how it works! how_the_cell_cycle_works.html * 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 14

15 Prophase: Mitosis! * 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!** 15

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 16

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

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

19 Cytokinesis begins cell is cleaved in half cell membrane grows to close both sides * done by a belt of protein threads *Results in 2 genetically identical cells! 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! 19

20 Let's see it in action! SO... The whole Mitosis process is like this: mitosis_and_cytokinesis.htm l 20