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Bio Chapter 2

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Overview of cell structure
...
Plasma membrane
"Fluid-mosaic" model
The membrane is composed primarily of
a double layer of phospholipids
The membrane is: polar or nonpolar
Polar
It consists of polar molecules with
hydrophilic heads (extension of membrane facing inside of cell and extension of cell) and hydrophobic lipid tails (inside membrane)
The membrane also contains
proteins
What kind of permeability?
Selective (let's some stuff in and some stuff stays out)
The membrane separates the
ICF and the ECF
It is made primarily of
phospholipids (lipid and water loving, charged part)
The nucleus is enclosed by a double layered..
Nuclear envelope
The nucleus contains
genetic material (DNA)
How does the nucleus direct protein synthesis?
It has the blueprint of cells to make proteins
The nucleus has genetic material that serves as the
blueprint during cell replication
DNA transcription
DNA to RNA (switches to this so cells can read the RNA)
RNA translation
RNA to protein
Cytoplasm
Portion of cell interior not occupied by the nucleus
The cytoplasm consists of
organelles and cytosol
Organelles
Distinct, highly organized, membrane-enclosed structures. Little organs
Cytosol
Goo/blood of cell, complex, gel-like mass in which the cytoskeleton is found
Endoplasmic reticulum
Elaborate fluid filled membranous system distributed throughout the cytosol. The network inside the cell. The cell's packaging center
Two types of ER
Smooth ER and rough ER
Rough ER
Surface has ribosomes attached to it. Ribosomes make proteins (manufacturing plant of the cell) (translation). Most abundant in cells which specialize in protein secretion (pancreas).
Smooth ER
No ribosomes attached, therefore not involved with protein synthesis. Package the proteins into vesicles.
The Smooth ER helps with the formation of
transport vesicles
Transport vesicles
Transport proteins made by rough ER
Secretory vesicle
Releases stuff into the plasma membrane to the outside of the cell
Smooth ER is involved with
lipid synthesis (cholesterol), steroid hormones, and detoxification of the liver (enzymes detoxify harmful compounds)
Free Ribosomes
Freely in the cytosol. Synthesis of proteins to be used in cytosol (as opposed to outside the cell).
Free ribosomes are the site of
RNA translation (RNA to protein).
Transcription
Complementary base pairing of free RNA nucleotides with their DNA counterparts in the exposed genes
Translation
Messenger RNA delivers the final coded message to the ribosomes for translation into an amino acid sequence to make a protein
Principles of Cell theory
The cell is the smallest structural functional unit capable of carrying over life processes. Function activities of each cell depend on structural properties (structure leads to function). Cells are living building blocks of all plant and animal organisms. All new cells and new life arises only from pre-existing cells.
The Golgi complex is known as the
The distribution center of the cell
Functions of the Golgi apparatus
The Golgi modifies the proteins secreted by the ER and prepares them for distribution. It sorts and directs finished products to their final destination
The Golgi is closely associated with the
ER
It consists of a stack of flattened, slightly curved, membrane-enclosed sacs called
cisternae
There are a number of Golgi complexes per
cell to secrete products outside the cell
Exocytosis
A process that allows the cell to secrete it products
Some vesicles (spheres of lipid with proteins in them) are transported to the plasma membrane to be secreted. These are
secretory vesicles
Others are distributed to other parts of the cell and these are called
transport vesicles
Exocytosis allows substances held inside the vesicles to be secreted...
from the cell
The vesicle moves toward the plasma membrane, binds with it, and then releases whatever is inside the vesicle to the
exterior of the cell
Endocytosis
Taking something into the cell
Pinocytosis
Non-selective. Cell drinking. Pinch off plasma membrane so it can "taste" the stuff outside to see what's going on.
Receptor mediated endocytosis
Receptor mediated endocytosis requires interaction of a specific molecule in the extracellular environment with a specific receptor protein in the cell membrane. Selective process where the cell will bind to hormones with receptors on the membrane.
Receptor mediated endocytosis is very
selective
How is insulin uptake done?
Receptor mediated endocytosis
Phagocytosis
White blood cells mostly. Cell eating. Limited to phagocytes (certain white blood cells).
Order of parts from nucleus on
Nucleus (control center), rough ER (packaging center), smooth ER (transport vesicles bud off), fusion with Golgi complex (distribution), secretory vesicles bud off and go to the plasma membrane, secretion (exocytosis)
Mitochondria is found in abundance in
muscle tissue
Mitochondria are
energy organelles
Mitochondria are major sites of
ATP production
Mitochondria contain enzymes for two process:
citric acid cycle (Kreb's cycle) and electron transport chain
Mitochondria have their own
DNA (they make proteins)
Mitochondria are enclosed by a
double membrane
Their inner in-folded membrane is called the
cristae
Cellular energy is
ATP
Energy in the cell is used to
1) Do mechanical things (cilia, muscles, etc.)
2) Transport things around the cell and across the cell membrane through membrane transport
3) Build things in the cell
Energy sources
1) Carbs
2) Lipids
3) Protein
How do we harvest energy (ATP) from these sources?
Equation of cellular respiration (net gain of 36 molecules of ATP from one glucose molecule)
Anabolic reactions
Use energy to build things (proteins, large energy storage molecules, etc.). Require energy.
Catabolic reactions
Break down those storage molecules and release energy. Typically that energy is used to do some sort of cellular work (release energy in heat)
The process of making ATP
Breaks down large energy storage molecules and creates ATP from them
Breaking bonds releases
energy
This energy is captured and stored
ATP in the cell (then used to make new things) (anabolic)
Three main processes of manufacturing ATP
Glycolysis, citric acid cycle (Krebs cycle), electron transport chain (ETC)
Glycolysis
Anaerobic in the cytoplasm with out oxygen. Breakdown of glucose (6 carbons) into 2 pyruvic acids (3 carbons each). Net 2 ATPs and a NADH molecule. Occurs in the cytosol.
More energy is made with
oxygen
Citric acid cycle (Krebs cycle)
Aerobic: requires oxygen. Takes place in the mitochondrial matrix. 2 ATPs.
Electron transport chain (ETC)
Aerobic: requires oxygen. Called oxidative phosphorylation because oxygen is require when you add the phosphate to ATP. So for every carbon glucose, you can get 34 ATPs. Adding phosphate to make ATP, makes a lot of ATP. 30 ATPs from NADH, 4 ATPs from FADH.
The process of anaerobic metabolism
Does not require oxygen. Glycolysis can occur without oxygen. Get 2 ATPs from glucose.
Krebs cycle and ETC cannot proceed without oxygen, so pyruvate made in glycolysis accepts the H+ from the NADH and this is made into
lactic acid.
The Life of Proteins
1) DNA strand in nucleus (genetic code)
2) DNA translated into RNA in the nucleus
3) Ribosomes translate the RNA to the protein
4) Protein packaged into a vesicle in ER
5) Golgi modifies the protein and directs its path in the cell. It arrives at location or secreted from cell through exocytosis.
6) Enabling function and secretion (function)
Where does glycolysis happen?
Cytoplasm (anaerobic, without oxygen)
Where do ETC and the Kreb cycle happen?
Mitochondria
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