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Cells
Cytology - the study of cells
Cells vary greatly in SIZE and STRUCTURE
Cells have two main parts - NUCLEUS & CYTOPLASM,
Enclosed in a CELL MEMBRANE (also called PLASMA MEMBRANE), which is extremely thin, often has folds and pouches, and allows certain substances to pass through it.
Selectively Permeable = controls what enters and leaves the cell, it allows some things to pass but not others, this is the MAIN FUNCTION of the cell membrane
CYTOPLASM - the area between the plasma membrane and nucleus. Where most metabolic reactions/activities take place. Filled with a clear fluid called CYTOSOL. Contains many structures called ORGANELLES
ORGANELLES
1. ENDOPLASMIC RETICULUM (E.R.) - complex system or network of interconnected membranes, canals, or channels. Connected to cell membrane, nuclear membrane, and organelles
Function = TRANSPORT SYSTEM
A. Rough ER - where ribosomes are located. Ribosomes manufacture (synthesize) proteins
B. Smooth ER - no ribosomes, where lipid synthesis takes place
2. GOLGI APPARATUS (BODIES) - series of flattened, membranous sacs near the nucleus
Function = "Refining", "Packaging", Delivery of proteins
3. MITOCHONDRIA (-ion = sing.) - Usually numerous, double layer membrane - inner layer folded to form CRISTAE.
Function = where chemical energy (food substances) is transformed into a useable form - molecules of ATP (adenosine triphosphate) that are like "packets" of energy. The process of releasing/transforming the energy from food involves OXYGEN and is called CELLULAR RESPIRATION
4. LYSOSOMES - quite variable in size and shape. Contain powerful digesting enzymes - breakdown and destroy foreign particles, microorganisms, damaged or worn out cells and cell parts
5. CENTROSOME (central body) - Usually near the G.A. and nucleus. Composed of 2 "cylinders" called CENTRIOLES (each composed of numerous microtubules), which always lie perpendicular to each other. Active involved in cell reproduction - SPINDLE forms from the centrioles
6. VESICLES - tiny sacs in which substances are transported
7. MICROFILAMENTS & MICROTUBULES - threadlike structures
MICROFILAMENTS - involved in cellular movement, as in muscle cells
MICROTUBULES - larger than filaments, maintain shape ("skeleton" of the cell)
The NUCLEUS - directs the activities of a cell. Contains GENETIC materials. Surrounded by a selectively permeable membrane called the NUCLEAR MEMBRANE or ENVELOPE. Filled with fluid called NUCLEOPLASM
1. NUCLEOLUS - small, dense structures within nucleus, made of proteins and RNA. No membrane
FUNCTION = produces ribosomes
2. CHROMATIN - loosely coiled "fibers" in nucleoplasm. Forms CHROMOSOMES during cell reproduction. Composed mainly of DNA (deoxyribonucleic acid) and PROTEIN. Contains coded information that directs protein synthesis in the cell
Movement of Substances Through the Cell Membrane
DIFFUSION - molecules move spontaneously (no cellular energy used) from an area of higher concentration to an area of lower concentration
FACILITATED DIFFUSION - molecules diffuse through a membrane by means of a carrier molecule transports (requires no energy = PASSIVE TRANSPORT)
OSMOSIS - the diffusion of water through a selectively permeable membrane. OSMOTIC PRESSURE = pressure to stop osmosis
SOLUTION
Solute = Substance dissolved
Solvent = Substance in which a solute is dissolved (usually water)
Hypertonic Solution = conc. of solute particles is greater outside the cell
Hypotonic Solution = conc. of solute particles is lower outside the cell
Isotonic Solution = conc of solute particles is the same inside and outside the cell
FILTRATION - molecules are forced through a membrane by hydrostatic pressure
ACTIVE TRANSPORT - molecules are moved against the concentration gradient. This requires the use of cellular energy, also usually involves a carrier molecule.
Exocytosis = transport of particles out of the cell
Endocytosis = transport of particles into th cell
Pinocytosis - liquids taken in, cell engulfs a droplet of water
Phagocytosis -solids taken in. a vesicle forms.
The Life Cycle of a Cell
A. Mitosis (nuclear division)
B. Cytoplasmic Division (cytokinesis)
C. Interphase (growth)
D. Differentiation - cells become specialized, developing characteristics in structure and function
MITOSIS
A. PROPHASE
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B. METAPHASE
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C. ANAPHASE
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D. TELOPHASE
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E. CYTOKINESIS
INTERPHASE - growth of cell occurs, chromosomes are duplicated and other structures and organelles are produced
DIFFERENTIATION - occurs as cells multiply and organism develops and grows
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Name:______
Cells
1. Cell:
A cell consists of three main parts---the ______, the cell "stuff" called ______, and the outer ______.
2. Cell Membrane: The cell membrane is extremely ______and is ______permeable.
function: The cell membrane regulates the______,
participates in signal transduction, and helps cells adhere to other cells
structure: The basic framework of the cell membrane consists of a double layer of ______
______are found in the cell membrane, including some which are transmembrane and some that are peripheral membrane.
3. Cytoplasm: The cytoplasm consists of a clear liquid called ______, a supportive ______, and networks of membranes and organelles.
4. endoplasmic reticulum: provides a tubular ______system inside the cell.
rough: why does it appear rough? ______
What does it function in the synthesis and transport of? ______
smooth: Why does it appear smooth? ______
What does it function in the transport of? ______
5. ribosome: Where are they found? ______
What are they composed of? ______
What do they help in the production of? ______
6. golgi apparatus: is composed of flattened ______and it packages the cells products.
These packages are released in the form of ______
7. lysosomes: contain ______enzymes to break up old cell components and bacteria.
They are sometimes called the "______" of the cell.
8. microfilaments and microtubules: are thin threadlike structures that serve as the ______of the cell.
Microfilaments, made of the protein ______, cause various cellular movements.
Mictotubules, made of the globular protein ______.
9. centrosome: is a structure made up of two hollow cylinders called ______. What is their function?
10. cilia & flagella: are motile extensions from the cell. Which one is shorter? ______
What is its function in the human body? ______
What is the only flagellated cell in the body? ______
11. Nucleus: is bounded by a ______-layered nuclear membrane containing relatively large nuclear ______that allow the passage of certain substances.
12. nucleolus: Where is it found? ______
Does it have its own membrane? ______
What chemicals is it made of? ______
13. chromatin: What chemicals is the chromatin made of? ______
14. Movement Through Cell Membrane:
The cell membrane controls what passes through it.
PASSIVE TRANSPORT: Mechanisms of movement across the membrane may be passive, requiring no ______from the cell (diffusion, facilitated diffusion, osmosis, and filtration).
diffusion: from area of ______concentration to area of low concentration to reach ______.
osmosis: Only substance that is moved by osmosis is ______.
What substances diffuse in the human body? ______
15. Facilitated Diffusion: - uses membrane proteins that function as ______to move molecules (such as glucose) across the cell membrane.
16. Filtration: Filtration forces molecules through ______and is commonly used to separate solids from ______
17. Active Transport: moves from area of ______concentration to area of ______
concentration. Requires ______proteins: (pumps). Also requires energy in the form of ______.
18. Endocytosis and Exocytosis: In ______molecules that are too large to be transported by other means are engulfed by an invagination of the cell membrane and carried into the cell surrounded by a vesicle.
______is a form in which cells engulf liquids.
______is a form is which the cell takes in larger particles, such as a white blood cell engulfing a bacterium.
In ______molecules are pushed out of the cell
19. Cell Cycle: The series of changes a cell undergoes from the time it is formed until it ______is called the cell cycle.
The cell cycle consists of what four stages? ______
The cell cycle is highly regulated. Most cells do not divide continually. Cells have a maximum number of times they can divide because of built-in "clocks"called ______on the tips of chromosomes.
20. Cell Reproduction: There are two types of cell division, mitosis and meiosis. Meiosis produces ______cells.
21. mitosis: How many daughter cells are produced in mitosis? ______Are they identical to the "mother" cell? ______
22. interphase: Interphase is a period of great metabolic activity in which the cell grows and 23. synthesizes new molecules and organelles. During the S phase of interphase, the ______of the cell is replicated in preparation for cell division.
24. prophase: What disappears during this phase? ______
What appears or becomes visible during this phase? ______
25. metaphase: Why is this phase the easiest to see on a microscope slide? (hint, what are the chromosomes doing?) ______
26. anaphase: What characterizes this phase? ______
27. telophase: What reappears during this phase? ______What have the chromosomes done? ______
28. Cytokinesis begins during anaphase of mitosis and continues as the cell pinches into ______
29. differentiation: The process by which cells develop into different types of cells with specialized ______is called differentiation. What controls this?
30. What is the death of a cell called? ______
Labeling Practice
Name:______Date:______
Cell Cycle Labeling
11. What moves the chromatids during mitosis? ______
12. What anchors the spindle? ______
13. What are the four phases of mitosis? ______
14. How many daughter cells are created from mitosis and cytokinesis? ______
15. During what phase does cytokinesis begin? ______
16. If a human cell has 46 chromosomes, how many chromosomes will be in each daughter cell? ______
17. If a dog cell has 72 chromosomes, how many daughter cells will be created during a single cell cycle? ______
.....Each of these daughter cells will have how many chromosomes? ______
18. The nuclear membrane dissolves during what phase? ______
19. In the cell pictured above, how many chromosomes are present during prophase? ______
20. What structure holds the individual chromatids together? ______
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