Chapter 3 Notes
Prokaryotic cells -Lack a nucleus Eukaryotic cell - Contain a nucleus and membrane bound organelleCell Membrane -Regulates what enters and leaves a cell
Cytoskeleton - Protein within a cell’s cytoplasm that gives the cell structure
Cytoplasm - Jellylike substance that supports organelles. It is made mostly of water that is necessary to dissolve nutrients for the cell to use.
Nucleus - Control center of the cell that directs all cell activities
Nucleolus - Site of ribosome manufacture within the nucleus
Chromatin - Chromosomes – long strands of DNA – that hold the code for protein manufacture within the cell
Endoplasmic Reticulum - Interconnected network of thin folded membranes that make proteins, fats, and carry out specific jobs as well as transporting them thru the cell
* Rough Endoplasmic Reticulum -Studded with ribosomes that make proteins for the cell membrane and other cells in the organism
* Smooth Endoplasmic Reticulum -Lacks ribosomes, it makes lipids and breaks down drugs and alcohol Ribosomes - Those that are loose in the cytoplasm make proteins used in chemical reactions within the cell.
Vesicles- Little sacs of ER that pinch off containing chemicals the cell needs for chemical reactions and take them to the Golgi Apparatus.
Golgi Apparatus - Closely layered stacks where proteins or fats are packaged, sorted, and delivered in or out of the cell for use or storage for later
Vacuole - Fluid filled storage sacs for water, food, ions, or enzymesMitochondria - “Powerhouse” of the cell where stored chemical energy (glucose) is combined with oxygen (burned) to release energy = cellular respirationLysosomes – animal cells only - Sacs filled with powerful enzymes for digesting foreign substances (bacteria, viruses, etc…) and recycling old cell partsCentrioles – animal cells only - Grow microtubules for use in cell division
Cell Wall – plant cells only - Outermost part of a plant cell that is made up of cellulose and supports the cell
Central Vacuole - plant cells only - Large vacuole that is filled with water and supports and strengthens the entire plant
Chloroplasts - plant cells only - Site of photosynthesis – they contain chlorophyll, a light absorbing molecule that converts solar energy into the stored chemical energy called glucose
Cell Membrane
Basic Structure
2 layers of phospholipids + Charged phosphate group and Glycerol = head that is polar and forms hydrogen bonds with water and Two fatty acid chains that are not polar and repel water and attract other fatty acid tails
Other molecules embedded in the cell membrane are:
∑ Cholesterol – for strength (animal cells only since plants have cell wall for strength
∑ Proteins for
o Helping materials pass through the membrane
o Part of the cytoskeleton
o Different cell types have different membrane proteins
∑ Carbohydrates attached to the proteins help cells identify each other
Fluid Mosaic Model
The cell membrane is flexible like a fluid and made up of different textures and patterns like a mosaic
Selective permeability (semipermeable or selectively permeable) – allows some but not all materials to pass through helping the cell maintain homeostasis by keeping ion and molecule concentrations at a healthy level inside the cell.
1. Small non-polar molecules can pass through easily (hormones)
2. Small polar molecules must pass through with the aid of a protein
3. Large molecules are carried through by vesicles
Cell Receptors – proteins that detect a signal molecule and react to it Intracellular – receptors “inside” the cell pick up small non-polar molecules called “ligands” that have entered the cell and take them where they need to go Membrane receptors – pick up ligands outside the cell, change shape, and pass molecules through
Passive transport is the movement of molecules across the cell membrane without energy input from the cell
1. Diffusion – the movement of molecules from an area of high concentration to an area of low concentration
o Concentration gradient is the difference from one location to the other
2. Osmosis – the diffusion of water
o Isotonic – solution that has the same concentration of dissolved particles as the cell
o Hypertonic - solution with a greater conc. of dissolved particles than the cell
o Hypotonic – solution with a lower conc. of dissolved particles than the cell
3. Facilitated diffusion – use transport proteins in the membrane to move larger molecules in and out of the cell from a high conc. to a low one
Active transport is the movement of molecules against the conc. gradient (from low to high) using transport proteins powered by chemical energy.
1. Endocytosis – taking liquids or large molecules into a cell by making a pouch in the cell membrane and pinching it off inside the cell where the vesicle fuses with a lysosome that digests the ingredients and the membrane releasing it back into the cell. Phagocytosis – “cell eating” a type of endcytosis for eating large foreign bodies like bacteria and killing them – white blood cells do this
2. Exocytosis – releasing molecules out of a cell by a vesicle attaching and fusing to the cell membrane and then pushing the contents out
Cell Membrane
Chapter 4 Notes
Section 4.1
All carbon based molecules store energy in their bonds but it is only available to cells after a series of complex chemical reactions that take place in the mitochondria.
ATP – adenosine triphosphate (tri = 3) is the molecule that transfers energy from the breakdown of food molecules to cell processes like building molecules or moving materials by active transport
See visual vocab p. 100
The energy is released when the third phosphate group, which is held on by a weak, unstable bond is removed. The molecule is now called ADP – adenosine diphosphate (di = 2)
ADP can become energy rich by adding a phosphate group back on. This is not a simple process and involves a large, complex group of proteins to complete the cycle.
ATP synthase – the enzyme that adds the phosphate group to the ADP making ATP
See fig. 4.2
Different foods yield different amounts of ATP after they are digested. Carbohydrates are the most common source of ATP and one molecule of glucose = 36 molecules of ATP. Fats, which are stored for energy use, yield 146 ATP’s. Proteins are rarely used for energy since the amino acids would be destroyed in releasing energy and they are necessary for building cell parts.
Photosynthesis captures light energy to make glucose that stores chemical energy.
Chemosynthesis takes place in dark areas and uses chemicals (sulfides) to make energy storing carbon-based molecules full of ATP.
Section 4.2
Chlorophyll a and b– the two pigments that are responsible for photosynthesis in chloroplasts, they absorb red and blue light waves and reflects the green
Chloroplast is made up of 2 main parts.
1. Grana – stacks of coin-shaped compartments called thylakoids (a thylakoid is one coin in the stack whose membrane contains the chlorophyll & proteins)
2. Stroma – fluid that surrounds that grana inside the chloroplast
2 Stages of Photosynthesis
1. Light-DEpendent
∑ Happen in the membranes of the thylakoids using water & light
∑ First – chlorophyll absorbs the light energy and breaks down the water molecules releasing oxygen gas
∑ Second – the energy is carried along the thylakoid membrane and transferred to ATP
2. Light – INdependent
∑ Happens in the stroma
∑ First – Carbon dioxide is added to a cycle of chemical reactions to build larger molecules using energy from the light dependent stage above.
∑ Next – one molecule of a simple sugar, usually glucose, is formed and the energy is stored in its bonds.
The simple sugars the plant makes can be used for energy or combined in complex chains to make starches and cellulose.
See fig. 4.5
Sec 4.5 Title: Cellular Respiration in Detail Prediction: There are 2 stages in the process of cellular respiration.
1. Why is glycolysis necessary? 1. ongoing in cytoplasm
1. anaerobic
1. takes 2 ATP to split glucose into 2 three-carbon molecules that get rearranged by enzymes to make pyruvate
1. Electrons get added to molecules called NAD forming NADH
1. 4 ATP get made, for a gain of 2 ATP
2. What happens in the Kreb Cycle? 2. Pyruvate + NADH + Oxygen enter mitochondria
2. pyruvate breaks down into one CO2 + one two-carbon molecule
2. many reactions continue ending up with 3 CO2 molecules as waste
2. one ATP
2. 4 NADH and 1 FADH2 to the electron transport chain
3. What happens in the electron transport chain? 3. in the mitochondria membrane the NADH and FADH pump H ions to an area of high concentration
3. H ions flow back through ATP synthase making ATP
3. get a net gain of 38 ATP and water
Section 4.6 Title: Fermentation
Predict: Fermentation is important because it makes ATP without oxygen.
Vocab – fermentation – anaerobic process that allows glycolysis to continue
Lactic acid – C3H6O3
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1. How does fermentation allow 1. fermentation removes electrons from glycolysis to continue
NADH and recycles NAD for glycolysis to use to pick up more electrons
1. once it gets more electrons the cell can continue to break down glucose and make a few ATP
1. instead of going into the citric acid cycle the pyruvate becomes lactic acid and the NAD goes back to break down more glucose into pyruvate and on and on…
1. our body cells do this when there is not enough oxygen to keep cellular respiration going and we are demanding a lot of energy
1. the lactic acid builds up in our cells and causes pain until we get enough oxygen and break it down and get rid of it
2. Why is it important? 2. it gives us needed energy
2. it flavors milk products (yogurt, cheeses)
2. alcoholic fermentation makes 2 molecules of alcohol (C2+) and 2 CO2 molecules with the 6 carbons from glucose and recycles the NAD just as above – yeast do this in breads & alcoholic beverages
2. bacteria break down food molecules in animals’ digestive tracts allowing us to absorb more nutrients from our food