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human anatomy and physiology
Transcript of human anatomy and physiology
Bailey Allison, Melanie Martir,
Trista Bailey A cell is the basic structural unit of living organisms Cell Theory activities of organisms depend on the individual and collective activities of its cell. cells vary in shape, size, and function seperates two of the bodys major fluids compartments, the intracellular, and the extracellular Plasma Membrane all cells are composed of carbon, hydrogen, nitrogen, and oxygen all human cells have 3 main parts, the plasma membrane, the cytoplasm, and the nucleus Lipid bilayers: are made up of phospholipids that has a polar "head" and its hydrophilic and an uncharged nonpolar "tail" made of two fatty acid chains and is hydrophobic Glycolipids: are phospholipids with attached sugar group but only on outer plasma membrane surface. Integral proteins: are involved in transporting and act as carriers. Peripheral proteins: attach to integral proteins and can act as enzymes or change cell shape during cell division and muscle contractions or link cells together Specialized Plasma Membrane Microvilli: shaggy hairs off plasma membrane and act as a stiffener Tight junctions: series of integral proteins fuse together to prevent molecules from passing through extracellular space. Gap junctions: a communicating junction between adjacent cells. Desmosomes: anchoring junctions that couple rivets on abutting cells and keep them from seperating. The passive process Passive process: substances cross membrane without energy input from cell. Diffusion: molecules/ions to scatter evenly. Transcription cannot begin until a gene-activation chemical called a Transcription Factor that stimulates loosening of the histones at the site-to-be of the gene transcription and then binds to the promoter.
The promoter is a special DNA sequence adjacent to the start point of the structural gene that specifies where mRNA synthesis starts and which DNA strand is going to serve as the template strand. Making the mRNA Complement Because the DNA gene is transcribed sequentially, the mRNA initially made, called pre-mRNA or primary transcript, is littered with intron "junk".
Before the newly formed RNA can be used as a messenger, t must be edited or processed into sections that is sections corresponding to introns must be removed.
Additionally, before the edited mRNA can become involved in protein synthesis, a number of specific RNA-binding proteins called mRNA complex proteins, must become associated with it. Editing of mRNA A translator takes a message in one language and restates it in another.
In the translation step of protein synthesis, the language of nucleic acids is translated into the language of proteins.
The newly formed mRNA attaches to the small ribosomal subunit by a leader sequence of bases that functions only to make this attaches to the small robosomal subunit by a leader sequence of bases that functions only to make this attachment. Translation Extracellular materials are any substances contributing to body mass that are found outside the cells.
One class of extracellular materials is body fluids, mainly interstitial fluid, blood plasma, and cerebrospinal fluid.
Most body cells are in contact with a jellylike substance composed of proteins and polysaccharides. These molecules are secreted by the cellsand self-assembled. Extracellular Materials A.In Isotonic solutions, cells retain their same size and same shape.
B.In a hypertonic solution the cells dehydrate and shrink.
C.In hypotonic solutions, cells take in water by osmosis until they burst. The Effect of Solutions of varying tonicities on living red blood cells Filtration is the process that forces water through a membrane by pressure from fluids.
Filtration is a passive transport that involves a gradient.
The gradient for filtration is a pressure gradient that pushes solute containing fluid from a higher pressure area to a lower pressure area. Homeostatic imbalance When a cell uses the bond energy of ATP to move solutes across the membrane, the process is active.
Active Transport Processes are distinguished by their source of energy.
In Primary Active Transport, hydrolysis of ATP results in a change in protein in such a matter that it pumps the solute across the membrane.
In Secondary Active Transport A single ATP powered pump can indirectly drive the secondary active transport of many other solutes. Active Processes Cell adhesion molecules play a key role in embryonic development, wound repair, and immunity. These sticky glycoproteins act as:
1. The molecular “velcro” that cells use to anchor themseves
2.The “arms” that migrating cells use to haul themselves past one another
3. SOS signals sticking out from the blood vessel lining that rally protective white blood cells to an infected area
4. Mechanical sensors that respond to local tension at the cell surface by stimulating synthesis or degradation of adhesive membrane junctions
5. Transmitters of intracellular signals that direct cell migration, proliferation, and specialization Roles of Cell Adhesion Molecules Membrane receptors are a huge and diverse group of integral proteins and glycoproteins that serve as binding sites
1. Contact Signaling – the actual coming together and touching of cells, the means by which cells recognize one another. This is important for normal development and immunity.
2. Chemical Signaling – signaling chemicals that bind specifically to plasma membrane receptors are called ligands. Among these ligands are neurotransmitters,hormones, and paracrines. G protein-linked receptors exert their effect indirectly through a G protein, which acts as a middleman or relay to activate a membrane-bound enzyme or ion channel.
3. Electric Signaling – the role of voltage-sensitive membrane channel proteins. Certain plasma membrane proteins are channel proteins that respond to changes in membrane potential by opening or closing the channel. Roles of Membrane Receptors Cytoplasm “the floor” is the cellular material between the plasma membrane and the nucleus.
1. Mitochondria – “The power house” provides most of the ATP supply, contain their own DNA and RNA, and are able to reproduce themselves
2. Ribosomes – site of protein synthesis
3. Endoplasmic Reticulum – “The transport system” continuous with the nuclear membrane, and there’s two different types: the rough ER and the smooth ER
4. Golgi Apparatus – “ The delivery system” modifies, concentrates, and packages the proteins and lipids made at the rough ER
5. Lysosomes – “The trash can” contains digestive enzymes, are large and abundant in phagocytes, dispose of invading bacteria and cell debris The Cytoplasm -Control center for cells (contains genes)
Multinucleate-Has many nuclei, signifies larger-than-usual cytoplasmic mass and must be regulated
Anuculeate- Mature red blood cells whose nuclei is ejected before it enters the blood stream. It cannot reproduce so it only lives in the bloodstream for 3-4 months.
Nuclear Envelope- A double membrane barrier separated by a fluid-filled space (similar to mitochondrial membrane)
Nuclear Pores- Intricate complex of proteins called the pore complex-forms passage channels and regulates what enters and exits the cell.
Nucleoli- Dark staining spherical bodies in nucleus (not membrane bound and typically only two per nucleus) The Nucleus -Microscopic, bumpy threads weaving through the nucleoplasm-composed of about 30% of DNA, genetic material is 60% of globular historic proteins, and about 10% is RNA chains(newly formed or forming)
Nucleosomes- consist of flattened, disc shaped clusters of eight histone proteins connected like beads on a string of a DNA molecule.
Chromosomes-When the cell is preparing to divide, chromatin threads coil and condense enormously to form short, barlike bodies called chromosomes. Chromatin Interphase-Period from cell formation to cell division
Subphase-G1 phase(Gap 1) cell is metabolically active, synthesizing proteins rapidly, and growing vigorously.
G0 phase-Cells that permanently stop dividing
S phase- DNA is replicated ensuring two future cells will be identical Cell Life Cycle Replisome- Large complex needed for DNA Synthesis to occur
DNA Primers- Made by primase enzymes which are a part of the replisome, Actual initiation of DNA synthesis requires formation of short (10 bases) RNA Primers
Once primer is in place, DNA Polymerase III is needed. Positions complimentary nucleotides along template strands then covalently bonds them.
DNA Ligase- Short segments of DNA are spliced together by DNA Ligase.
Semi Conversive Replication- Each new molecule made from DNA Ligase = one new and one old nucleotide strand. This mechanism of DNA Replication is called Semi conversive replication.
Chromatids- Chromatin strands united by button-like centromere, condense to form chromatids. DNA Replication Mitosis Cell division
Mitosis Cleavage Furrow- Created by the activity of a contracile ring made from actin fragments.Plasma Membrane over the center of the cell drawn inward forms the cleavage furrow.
Cdks( cyclin-dependant kinases. Cyclins( regulatory proteins whose levels rise and fall during each life cycle.
Cdks is present in a constant concentration in the cell and are active by binding to particular cyclines.
MPF-(M phase promoting factor) Is required to give the okay signals to pass the G2 checkpoint and enter the M phase.
Triplets- Each sequence of 3 bases
Exons Most genes of higher organisms contain these, amino acids-specifying information sequences separated by introns, which are non coding, often repetitive segments that range from 60-100,000 nucleotides Control of Cell Division Transfer RNA-(tRNA) small roughly clover-leafed shaped molecules.
Ribosomal RNA-(rRNA) Part of ribosome
Messanger RNA-(mRNA) Long nucleotide strands resembling "Half DNA" molecules
Genetic code- Rules by which base sequence of a gene is translated into an amino acid sequence.
Transcription- Involves transfer of information from DNA gene's base sequence to complimentary base sequence of mRNA molecule. Role of RNA Spherical membranous organelles containing digestive enzymes.
Function as a cell's "demolition crew."
Degrades worn out or nonfunctional organelles
Breaks down bone to release calcium ions into the blood. Lysosomes Secretory Lysosomes - found mainly in white blood cells, immune cells and melanocytes.
Autolysis - Basis for desirable destruction of cells. System of ogranelles that work together to
1. Produce, store and export biological molecules.
2. To degrade potentially harmful substances.
ER, Golgi apparatus, secretory vesicle and lysosomes. Endomembrane System Microtubules Cytoskeleton Series of rods running through the cytosol
Cell skeleton. acts like a cells "bones," "muscles" and "ligaments." Hollow tubes
Made of spherical protein subunits called tublins
Determine the overall shape of the cell. Microfilaments The thinnest element of the cytoskeleton
strands of the protein called actin
Involved in cell motility or change in cell shape. Intermediate filaments Tough insoluble protein fibers.
Like woven ropes
Most stable and permanent.
Act as internal guy-wires to resist pulling forces excerted on the cell. Centrosomes and Centrioles Act as a microtuble organizing center
contain centrioles - small barrel shaped organelles oriented at right angles
The Centrosomes matrix is best known for its generation of microtubules and organizing the mitotic spindle. Cell Extension Cilia - Whip-like cellular extension that occur on the exposed surface of certain cells. When a cell is about to form cilia, ccentrioles multiply.
When the projections formed by cenrioles are substantially longer they are called flagella(ex: sperm tail) Basal Bodies - Centrioles forming the base of cilia and flagella
Composed of dynein protein