Exchange with the Environment 4 -1
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Transcript of Exchange with the Environment 4 -1
Exchange with the Environment4-1
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:
2.) Active Transport - uses energy
We will talk more about this in a bit...
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html
Let's see it in action!
Osmosis – movement of water across a selectively permeable membrane in response to a high solute concentration
Ex:
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
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html
Let's see it in action!
solute particle water molecule
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/
http://www.college-cram.com/study/biology/cell-membranes/exocytosis/Let's see how it works!
Photosynthesis is how plants obtain energy!~ done by autotrophs
Cell Energy!4-2
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
ATP
cellular respiration
CO2 + H2O
mitochondria
3 steps:
1.) Plants harvest energy from the sun~ thylakoids – contain chlorophyll - within the chloroplastEx:
Chlorophyll is a pigment that absorbs red and blue but reflects green and yellow
Also have carotenoids – absorb green and bluereflect red, orange and yellow
~ where we get the fall leaf colors!
2.) Light reactions produce energy
3.) Dark reaction produces sugars
~ uses light energy to make some ATP
~ use the ATP from the light reaction to make glucose!
~ "Dark" because it doesn't use light!!
http://www.science.smith.edu/departments/Biology/Bio231/ltrxn.html
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
O2 not present = pyruvate converted to lactic acid or ethyl alcohol ~ anaerobic - w/o O2
Here's how it works:
glucose
pyruvate
ethyl alcohol or
lactic acid
ATP
AnaerobicAerobic
mitochondria
O2 availableO2 NOT available
ATP
Connection between Photosynthesis and Cell Respiration
C6H12O6 + O2 CO2 + H2O + 36ATP
Light + CO2 + H2O C6H12O6 + O2
These are the chemical equations for both processes...notice anything?
Cell Resp.:
Photosynthesis
One cannot be without the other!
They form a continuous cycle!
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!
The Cell Cycle4-3
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:
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:
centromere
chromatid chromatid
chromosome
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
*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!
Homologous
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 = nondisjunctionie: 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 YThe 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
Mitosis and the Cell Cycle4-3
Your book says the cell cycle is in 3 stages:
1 - Interphase2 - Mitosis3- 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
* 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…
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html
Let's see how it works!
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!**
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
Anaphase:
* centromere divides and the 2 chromatids separate
* the new chroms. move to opposite sides as the spindle fibers shorten
Telophase:* chroms uncoil at either end of cell
*new nuclear envelope forms
* spindle fibers break down and disappear
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!
SO... The whole Mitosis process is like this:
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html
Let's see it in action!