An adult human body consist of
50 - 100 trillion cells
A composite cell - 3 major parts
1) nucleus-contains the DNA, which directs the cell's functions.
2) cytoplasm-is composed of specialized structures called cytoplasmic organelles.
3) cell membrane-the cytoplasm surrounds the nucleus and is contained by the cell membrane.
What is a differentiated cell?
A cell with specialized characteristics and are formed by less specialized cells. They also have distinctive shapes that carry out their functions.
Distinguish between the cytoplasm and cytosol of a cell.
Cytoplasm is composed of specialized structures called cytoplasmic organelles. Cytosol is the liquid matrix of the cytoplasm. The organelle is suspended within this liquid.
Explain the general function of organelles.
A structure or compartment in cells that houses the biochemical reactions that carry out a specific function. They are composed as assemblies of large molecules, proteins, carbs, lipids, and nucleic acids
Describe three types of differentiated cells.
1) Nerve Cells-threadlike extensions many centimeters long transmit nerve impluses from one part of the body to another.
2) Epithelial Cells-line the inside of the mouth are thin, flattened and tightly packed like floor tile. They form a barrier that shie
Define selectively permeable.
Maintains the integrity of a cell, the cell membrane controls the entrance and exit of substances. The cell membrane is crucial as it is a conduit between the cell and the extracellular fluids in the body.
Describe the structure of a cell membrane and explain how this structural organization provides its function
Mainly composed of lipids and proteins, some carbs.Basic framework is a double layer (bilayer) of phospholipid molecules that self assemble so that their water-soluble heads containing phosphate groups, form the surfaces of the membrane, and their water i
Three functions of membrane proteins
1) Integral protein- a protein that spans the membrane.
2) Peripheral protein- a protein that projects from the membrane's outer surface.
3) Transmembrane protein- a protein that extends outside the cell membrane at one end and dips into the cytoplasm on
State the way that cellular adhesion is essential to health and a way that abnormal cellular adhesion harms health.
Cellular adhesion molecules enable cells to stick to each other, aiding in blood clotting or providing traction. They guide cells on the move. CAM cells help establish the connections between nerve cells that underlie learning and memory. Lack of Cellular
Types of membrane proteins
1) receptor proteins-receive and transmit messages into a cell.
2) integral proteins-form pores, channels, and carriers in cell membrane to respond and to receive incoming messages.
3) Enzymes-catalyze chemical reactions.
4) cellular adhesion molecules-en
Cytoplasmic organelles have specific functions: Ribosomes
1) Ribosomes-tiny spherical structures composed of protein and RNA. Provide structural support and enzymatic activity to link amino acids to form proteins. They are scattered within the cytoplasm.
The activities of a cell occur largely in its cytoplasm...
where nutrient molecules are received, processed, and used in metabolic reactions.
Cytoplasmic organelles have specific functions: Endoplasmic reticulum
Endoplasmic reticulum is a complex organelle composed of membrane bound flattened sacs, elongated canals and fluid filled vesicles. They provide a tubular transport system for molecules throughout the cell. It participates in the synthesis of protein and
Endoplasmic reticulum cont.
It is wide spread in the cytoplasm and the outer surface is studded with many ribosomes this is called rough ER. The ER that lack ribosomes are smooth ER. it contains enzymes important to synthesizing lipids, absorbing fats from the digestive tract. They
Cytoplasmic organelles have specific functions: Vesicles
are membranous sacs that vary in size. They may form when a portion of a cell membrane folds inward and pinches off. Fleets of vesicles transport many substances into and out of cells in a process called vesicle trafficking.
Cytoplasmic organelles have specific functions: Golgi apparatus
a stack of flattened membranous sacs called cisternae. This organelle refines, packages and delivers proteins synthesized on the rough ER. They arrive at the Golgi via enclosed tiny vesicles composed of membrane from the ER.
Cytoplasmic organelles have specific functions: Mitochondria
are elongated fluid filled sacs. They move slowly in the cytoplasm and can divide. Contains small amt of DNA that encodes info for making a few types of proteins.
Mitochondria has two layers
1) Inner membrane and outer membrane -folded shelflike partitions called cristae. This dramatically increases the surface layer where chemical reactions can occur. The mitochondria captures and transfers newly released energy into special chemical bonds o
Cytoplasmic organelles have specific functions: Lysosomes
are the garbage disposals of the cell, where enzymes dismantle debris. They are tiny membranous sacs that contain powerful enzymes that break down proteins, carbs and nucleic acids. Lysosomes destroy worn out or damaged cells. An abnormality in one of the
Cytoplasmic organelles have specific functions: Peroxisomes
are membranous are present in all human cells but prevalent in cells of the liver and kidneys. They catalyze metabolic reactions that release hydrogen peroxide. They catalyze a variety of biochemical reactions; sythesis of bile acids, breakdown of lipids,
Cytoplasmic organelles have specific functions: Centrosomes
It is nonmembranous and consists of two cylinders called centrioles. Lie on right angles to each other. They migrate to either side of the nucleus, where they form spindle fibers that pull on and distribute chromosomes which carry DNA info for new cells
Cytoplasmic organelles have specific functions: Cilia and Flagella
are motile extensions of certain cells. Cilia fringe the free surfaces of some epithelial cells. Cilia dot cells in precise patterns. They move in a coordinated manner. flagella-longer and a cell usually has just one. A wavelike motion at its base. The ta
Cytoplasmic organelles have specific functions: Microfilaments & microtubules
Microfilaments-tiny rods of the protein actin that form bundles and provide certain cellular movements.
Microtubules-long, slender tubes composed of the globular protein tubulin. Rigid, which help to maintain the cell shape. Provide movement. Move organel
Inclusions
Cytoplasms contain chemicals called inclusions. Normally temporarily in a cell. Inclusions store nutrients such as glycogen, lipids and pigments.
Cell Nucleus-is a large spherical structure that contains...
the genetic material DNA that directs the activities of the cell.
The nucleus is enclosed in a double layered ...
nuclear envelope, which consists of an inner and an outer lipid bilayer membrane. They have a narrow space between them but are joined at the opening of the nuclear pores.
List the parts of the nucleus-nucleolus
1) Nucleolus-small dense body composed of RNA and protein. Has no surrounding membrane and is formed in specialized regions of the chromosomes. This is the site of ribosome production, once formed they migrate through the nuclear pores to the cytoplasm
List the parts of the nucleus-chromatin
2) loosely coiled fibers in the nuclear fluid. Composed of continuous DNA molecules wrapped around clusters of protein called histones * looks like beads on a string.Chromatin is the material that becomes organized and compacted to form chromosomes.
Movement into and out of the cell
The cell membrane is a barrier that controls which substances enter and leave the cell. Oxygen and nutrient molecules enter through the membrane. Carbon dioxide and other waste exit the membrane
Passive process - movement mechanisms
Diffusion, osmosis, facilitated diffusion and filtration
Active process - movement mechanisms
Active transport, endocytosis and exocytosis.
Diffusion-passive movement
atoms, molecules and ions in a liquid or air solution move from areas of higher concentration to areas of lower concentration. This becomes evenly distributed or more diffuse.
Diffusion cont.
diffusion of a substance across a membrane can occur only if:
1) the cell membrane is permeable to that substance
2) a concentration gradient exists such as that the substance is at a higher concentration on one side of the membrane or the other. Diffusio
Facilitated Diffusion-passive movement
...ions of sodium, potassium and chloride may diffuse through protein channels in the membrane. This type of movement follows the concentration gradient but uses membrane proteins as "carriers" so it is termed facilitated diffusion. This is important not
Osmosis-passive movement
is the movement of water across a selectively permeable membrane into a compartment containing solute that cannot cross the same membrane...water follows salt. Water moves by osmosis. Protein is impermeable, so equilibrium can be reached by movement of wa
Isotonic-passive movement
osmotic pressure of the intracellular and extracellular fluids is the same. Any solution such as saline, that has the same osmotic pressure as body fluids is called isotonic. Cells will not change in size.
Hypertonic-passive movement
Solutions that have a higher osmotic pressure than body fluids are called hypertonic. More water leaves than enters so cells shrink. If move water enters and leaves, cell swell and may burst.
Filtration-passive movement
Molecules move through membranes by diffusion because of their random movements. IN other instances, molecules are forced through membranes by the process of filtration. It is commonly used to separate solids from water. Gravity forces water through filte
Filtration in the body
blood pressure forces smaller molecules through tiny openings in the capillary wall. The larger molecules remain inside.
Active Transport-active movement
active transport moves molecules against their concentrated gradient. During active transport, a molecule or ion combines with a carrier protein, whose shape changes as a result. This requires cellular energy, transports the particle across the cell membr
Endocytosis-active movement/cellular energy
Cellular energy is used to move substances into or out of a cell. Molecules or particles that are too large to enter a cell by diffusion or active transport are conveyed in a vesicle that forms from a section of the cell membrane.
Three forms of endocytosis-pinocytosis
1) Pinocytosis-cells take in tiny droplets of liquid from their surroundings. When this happens, a small portion of the cell indents. This seals off and produces a vesicle (fluid filled) and detaches from the surface and moves into the cytoplasm.The liqui
another form of endocytosis-phagocytosis/cellular energy
2) phagocytosis-this cell takes in solids rather than liquids. certain types of cells are called Phagocytosis including white blood cells. They can take in bacteria and cellular debris and attaches to the cell membrane. Phagocytosis is an important line o
another form of endocytosis-receptor-mediated endocytosis/cellular energy
3) receptor-mediated endocytosis-moves very specific types of particles into the cell. A specific molecule binds to a receptor protein, forming a receptor ligand combination. The binding of the ligand to the receptor protein stimulates the cell membrane t
Exocytosis-active movement/cellular energy
vesicles fuse with membrane and release contents outside of cell, such as newly synthesized proteins.
Transcytosis-active movement/cellular energy
combines receptor-mediated endocytosis and exocytosis to ferry particles through a cell. ex. HIV crossing a cell layer. Infects white blood cells and virus buds. Transcytosis is specific. Uses cellular energy
The cell cycle has several distinct stages
1) Interphase
2 )Mitosis
3) Cytoplasmic Division
4) Differentiation
Interphase
Very active period. During interphase, the cell grows and maintains its routine functions. It cell is programmed to divide, it must amass important biochemicals and duplicate much of its contents so that two can form from one. DNA is structured during the
Mitosis
Mitosis is a form of cell division that occurs in somatic cells and produces two daughter cells from the original cell. Genetically identical with 46 chromosomes. During mitosis, the nuclear contents divides called Karyokinesis meaning nucleus movement.
Mitosis Cont...
the cytoplasm is apportioned into two daughter cells in a process called cytokinesis meaning cell movement. The chromosomes were duplicated in interphase, but it is in mitosis that the chromosome sets evenly distribute between the two forming cells. Mitos
Recap Interphase & Mitosis
The cell cycle is divided into interphase(when cellular components duplicate and when cells split in two)distributing its contents into two daughter cells. Interphase is divided into two gap phases (G1 & G2 cell growth), when genetic material DNA duplicat
1st phase of mitosis-prophase
one of the first indications that a cell is going to divide is the condensation of chromatin fibers into tightly coiled rods. Centrioles move to opposite sides of cytoplasm and the nuclear envelope and nucleolus disperse. Microtubules assemble and associa
2nd phase of mitosis-metaphase
spindle fibers from the centrioles attach to the centromeres of each chromosome and align themselves center or midway between the centrioles
3rd phase of mitosis-anaphase
the centromeres separate and these identical chromatids are now considered individual chromosomes. The separated chromosomes move in opposite directions, movement results from microtubule activity. The spindle fibers shorten and pull their attached chromo
4th phase of mitosis-telophase
final stage of mitosis begins when the chromosomes complete their migration toward the centrioles. Much like the reverse of prophase. As the identical sets of chromosomes approach their respective centrioles, they begin to elongate and unwind from rodlike
Why is precise division of the genetic material during mitosis important?
Precision is important so that each new cell receives a complete copy of the genetic info.
Explain how meiosis differs from mitosis
meiosis is a form of cell division that occurs only in the cells that give rise to sex cells (sperm and eggs). Meiosis halves the chromosome number until a sperm cell fertilizes an egg cell completing the 46 chromosomes. Mitosis is a form of cell division
How do cells vary in their rate of division?
factors that effect the rate of cell division are:
1) Levels of protein called kinases and cyclins control the cell. When protein levels change so does cell rate
2) DNA are found at the tips of chromosomes called telomers, each mitosis removes up to 1200
Controlling cell division is crucial to health
Frequent cell division-an embryo could not develop, a child could not grow, a wound could not heal, abnormal growth, and may also form a disorganized mass called tumor.
2 types of genes cause cancer
Oncogenes-are abnormal variants of genes that normally control the cell cycle, but are over-expressed and increasing cell division.
Tumor suppressor genes-normally hold mitosis in check. When they are removed it results with an uncontrolled cell division
Cancer
may also be the consequence of a failure of normal programmed cell death, resulting in overgrowth.
Characteristics of cancer cells
1) Loss of cell cycle control
2) Heritability-cancer cell divides to form more cancer cells.
3) Transplantability
4) Dedifferentiation-loss of specialized characteristics
5) Loss of contact inhibition
6) Angiogenesis-ability to induce local blood vessels
Steps in the development of cancer
1) Cancer trigger: inherited mutation or enviromental insult.
2) Oncogene turned on (or) Tumor suppressor gene turned off.
3) Invasion and metastasis- cancer grows and spreads by inducing formation of blood vessels to nourish them and then break away from
Stem and progenitor cells
1) Stem cell divides to yield another stem cell and a partially differentiated progenitor cell.
2) Cells that give rise to any differentiated cell type are totipotent.
3) Cell with more restricted fates are pluripotent.
4) Stem cells may be present in adu
Apoptosis-Cell Death
A cell that does not divide or differentiate has the option to die.
Cell Death
1) Fast, orderly multistep process that begins when a cell surface receptor receives a signal to die. Caspases start a chain reaction that cuts up the cell into membrane -encapsulated pieces (becomes deformed), and finally a phagocyte attacks and engulfs