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Cells
The building blocks of the human body.
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Cytoplasm
Surrounds the nucleus & contains a fluid cytosol & intracellular structures called organelles.
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Cytosol
Fluid that surrounds the nucleus. Differs in composition from the extracellular fluid that surrounds most cells of the body.
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Diffusion
Net movement of material from an area where concentration is relatively high to an area where its concentration is lower. It occurs until the concentration gradient is eliminated.
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Endocytosis
- Packaging of extracellular materials in a vesicle at the cell surface for import into the cell.
- 1) receptor mediated (active process)
- 2) pinocytosis ("cell-drinking")
- 3) phagocytosis ("cell-eating"
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Exocytosis
Functional reverse of endocytosis.
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Endoplasmic Reticulum (ER)
Network of intracellular membranes.
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Rough Endoplasmic Reticulum (RER)
Contains ribosomes & is involved in protein synthesis.
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Smooth Endoplasmic Reticulum (SER)
Does not contain ribosomes; it is involved in lipid & carbohydrate synthesis.
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Gene
A functional unit of heredity, & each gene consists of all the triplets needed to produce a specific protein.
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Chromasome
Its DNA sores information used by the nucleus to direct the synthesis of specific proteins.
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Golgi Apparatus
Forms secretory vesicles & new membrane components, & it packages lyosomes. Secretions are discharged from the cell by exocytosis.
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Mitochondria
Responsible for 95% of the ATP production within a typical cell. The matrix, or fluid contents of a mitochondrion, lies inside cristae, or folds of an inner mitochondrial membrane.
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Vessicle
A membranous sac in the cytoplasm of a cell.
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Secretory Vessicle
Contains secretions that will be discharged from a cell.
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Lysosome
Vesicles filled with digestive enzymes. Functions include ridding the cell of bacteria & debris.
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Peroxisome
Smaller than lysomes & carry a different group of enzymes. They arise from the growth & subdivision of existing peroxisomes.
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Nucleus
Control center for cellular operations. Surrounded by a nuclear envelope, through which it communicates with the cytosol by way of nuclear pores.
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Osmosis!!
The diffusion of water across a membrane in response to differences in concentration.
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Osmotic Pressure
The force of movement of water across a membrane in osmosis.
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Phagocytosis
"It is a form of endosytosis. "cell-eating" produces vesicles that contain solid objects.
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Protein Synthesis
Includes both transcription & translation.
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Transcription
Part of protein synthesis. It is the production of RNA from a single strand of DNA. It takes place within the nucleus.
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Translation
The assembling of a protein by ribosomes, using the information carried by the RNA molecule. It takes place in the cytoplasm.
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Receptors
It is sensitive to a particular environmental change or stimulus.
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Functions of Cell Membranes
- 1) physical isolation
- 2) Control of the exchange of materials
- 3) sensitivity
- 4) structural support
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Cell Membrane (or Plasma Membrane) Contains...
- 1) lipids
- 2) proteins
- 3) & carbohydrates
- (Its major components, lipid molecules, form a phospholipid bilayer.)
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Membrane proteins may function as...
1) receptors 2) channels 3) carriers 4) enzymes 5) anchors 6) identifiers
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Filtration
Hydrostatic pressure forces water across a membrane. If membrane pores are large enough, molecules of solute will be carried along with the water.
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Facilitated Diffusion
A type of carrier-mediated transport & requires the presence of carrier proteins in the membrane.
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Active Transport Mechanism
Consumes ATP & are independent of concentration gradients. Some ion pumps are exchange pumps.
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Vesicular Transport
Material moves into or out of a cell in membranous sacs.
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Membrane-enclosed Organelles
- Surrounded by lipid membranes that isolate them from the cytosol. Membranous organelles include:
- 1) endoplasmic reticulum
- 2) the nucleus
- 3) the Golgi appraratus
- 4) lysomes
- 5) mitochondria
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Nonmembranous Organelles
- Always in contact with they cytosol.
- 1) cytoskeleton
- 2) microvilli
- 3) centrioles
- 4) cilia
- 5) flagella
- 6) proteasomes
- 7) ribosomes
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Cytoskeleton
- Gives the cytoplasm strength & flexibility. Main components:
- 1) microfilaments
- 2) intermediate filaments
- 3) microtubules
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Microvilli
Small projections of the cell membrane that increase the surface area exposed to the extracellular enviroment.
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Centrioles
Direct the movement of chromosomes during cell division.
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Flagella
Move a cell through surrounding fluid rather than moving fluid past a stationary cell.
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Ribosome
Intracellular factory that manufactures proteins. 1) free ribosomes are in the cytoplasm 2) fixed ribosomes are attached to the endoplasmic reticulum.
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Proteasomes
Remove & break down damaged or abnormal proteins.
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