Cell Biology: Structure & Function of Ribosomes, Chromatin, Mitochondria, & Cell Membranes, Study notes of Biology

Download Cell Biology: Structure & Function of Ribosomes, Chromatin, Mitochondria, & Cell Membranes and more Study notes Biology in PDF only on Docsity! Chapter 4: Cell Structure and Function 09/19/2011
Ribosomes = protein builder/ build cell’s protein
Chromatin= component of chromosome/ Composed of DNA and proteins
Chromosome number differs based on species (2n=46 for human beings).
Each cell has 23 set of chromosome and then makes a copy of it.
Billion of sexual cells are produced for male while only women ovulate only once a month  birth control prevents ovulation by making hormones (estrogens and
Males produce sperms all their life while women stops around 40-50 years old (to be checked)
Sperm is produced for reproduction
Each partner gives 23 chromosomes to give the baby 46
Chromatin looks like a long thin …
Ribosomes are cytoplasmic complexes which are the sites of protein synthesis (where they are made)
(Most important biological protein in our cells)Polyribosome(long chain of ribosome on mRNA)  makes protein
Cells have a huge need for protein
Ribosome has two parts and is found in different parts dependent on cell. (free in cytoplasm for prokaryote and either free or attached to membrane of the endoplasmic reticulum for eukaryotes)
If your cells stop making mRNA, the cell will not be able to translate the information in DNA into protein. WITH NO PROTEIN, CELLS WOULD DIE
Fig. 4.14:
Endoplasmic reticulum: Smooth ER (main function: Make lipids)  no ribosomes attached to it while rough ER  ribosomes attached to it (Make proteins and manufacture membranes)

//09-21-2011

Smooth and Rough are attached to each other
Proteins get made in rough ER that move through membrane ER to then packed into vesicle which then travels to the Golgi Complex.
The Golgi Complex has two sides: 1st receives package and 2nd ships them
Golgi stops working, you can still make protein but they wont be sent anywhere.
Lysosome is a vesicle that helps 1-breaking macromolecules(lipids, carbohydrates, proteins and …) and 2-recycling macromolecules. (Extremely important for cellular function)
Mitochondria: Food  ATP (All cells require ATP energy)
Chloroplasts: Energy from sunlight
They both contain ribosome and DNA.
They both can grow and reproduce.
You can increase energy requirement by exercising. You put into a lot more stress than they needed to (cells become more and more Mitochondrion).
Muscle weight more than fat because of polar and non polar bounds.
Mitochondria, chloroplast and prokaryotic cells all have their own DNA and ribosomes.
Chloroplasts contains chlorophyll (absorbs sunlight to make glucose through photosynthesis)
Carbohydrates all have C6H12H6 formula.
The Stroma: is the space between the inner membrane.
Chloroplasts have three set of membranes (Inner membrane, thylakoid and Stroma)
Grana is a stack of thylakoid
Mitochondria: are organ cells which use energy extracted from organic macromolecules to produce ATP  Process is called respiration
#Mitochondria depends on how much energy the cell needs
Cells energy requirement of my heart require more than my muscle cells because they are always working.
Cristae are inner membrane with infolded structures.
intermembrane space is the space between inner and outer membranes is called
Some things get to the membranes a little more than others

// 09/26/2011

Selective permeability is the property of biological membranes which allows some substances to cross more easily than others.
2 factors determine permeability:
solubility: Characteristics of the substance crossing the membrane
Facilitated diffusion by a carrier protein or a channel protein Phospholipid diffusion through the phospholipid bilayer Aquaporin : specialized protein channel transports water across the membrane  they are composed of hydrophilic amino acids Without hydrophilic, we will need to drink more water to survive. Osmosis through aquaporin Specialized proteins allow things to move along gradient Facilitated diffusion is a diffusion across a membrane with the help of protein. Three main categories of diffusion: 1. Bind and release  Glucose is polar  wont get across a non polar 2. Selective channel  A pore the size of the solute  charge is right, it will get through  like drinking a smoothie (if particles are small enough to get through the straw, then it will get through) 3. Gated channel  Like a selective channel only with a door.  presence of neurotransmitter (it is like a gated process) 10 glucose molecules Osmosis: Hard process for most students  Osmosis is focused on movement of water molecules Osmosis: water moves from a less to a more concentrated area to dilute ( you make yourself a drink, and if you put too much vodka in it  it is too strong, then you add more red bull in it)  TEST question: where is the water going to go ?? The following terms can only be used to compare to something else: Isotonic  the same Hypertonic  Over Hypotonic  less than/ beneath The Environment is outside the cell, not INSIDE. If cell is placed in hypotonic environment  then outside has to be lower  water goes from low to high  water adds mass, so mass of cell will increase if placed in hypotonic environment In isotonic environment Hypertonic environment: water rushes into the cell, causing it to swell (mass of cell will slowly decrease). Energy requiring transport across membranes: Pumps  something that requires energy Active transport: is an energy requiring process during which a transport protein pumps a molecule across a membrane against its concentration gradient. - Energy requiring - Uses energy from ATP - Used to maintain ion gradients (e.g. Ca2+ ) ATP is the active transport of energy source Endocytosis is the cellular uptake of large molecules( aka macromolecules) and particulate substances (foods) by the localized pinching off of a region of a region of the plasma membrane to form a vesicle Three main mechanisms: - phagocytosis - Pinocytosis - Receptor mediated endocytosis Phagocytosis is the endocytosis of solid particles This may involve the formations of pseudopodia Phagocytosis  solid (big) molecule being transported into cells Pinocytosis  transporting fluids or liquids into cells Receptor mediated endocytosis  targets specific proteins/ macromolecules / receptors have to match the molecules targeted Cardiovascular Disease  it is the #1 cause of Death in US/ LDL receptors for low density lipoproteins Cells want to remove cholesterol Organism with fewer LDL receptors have more chances to suffer heart disease. Clinical depression  unhappy for no reason (they do not know what that is) SSRI’s “selective Serotonin Re-Uptake Inhibitors” Get more used of the serotonin we are already producing Love produces the same amount of serotonin as eating chocolate. Exocytosis moves material out of the cell. Exocytosis is the cellular secretion of large molecules (a.k.a macromolecules) by the fusion of vesicles with the plasma membrane. Desmosomes  Connection between cells  one cell next to another Tight Junctions  if the connection between cells needs to be watertight.  numerous protein sealing cells and preventing water from coming out. Cells communicate between them through gap junctions (animals) or plasmodesmata (plants)  proteins channel from different cells  Important in very quick response of the nervous system Water is needed by the plants for photosynthesis in the Leafs Tight junctions are necessary to prevent solids from leaking. Gap Junctions are lined up so animal cells can communicate with one another.