Cytology

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Cell

Cell

basic unit of life

Organelles

specialized structures

Nucleus

contains genetic material

Cytoplasm

living material

Plasma membrane

encloses the cytoplasm and nucleus

Functions of the Cell (CSCR)

1. Cell metabolism and energy use. 2. Synthesis of molecules. 3. Communication. 4. Reproduction and inheritance.

Cell Membrane

Outer boundary of the cell

Cell Membrane

Determines what enters and leaves the cell

Extracellular

substances outside the cell

Intracellular

substances inside the cell

Fluid-Mosaic Model

arrangement of molecules in the cell membrane

Selectively permeable

allows some substances to pass into or out of the cells

Diffusion

Movement of a solute from an area of higher to lower concentration gradient

Concentration gradient

difference in the concentration of a solute in a solvent minus the concentration of the solute at another point

Leak channels

allow ions to pass through

Gated channels

limit the movement of ions across the membrane

Osmosis

Diffusion of water across a selectively permeable membrane

Osmotic pressure

force required to prevent movement of water across a selectively permeable membrane

Hypotonic

lower concentration

Isotonic

same concentration

Hypertonic

higher concentration

Lysis

when cells swell, then ruptures

Crenation

cell shrinking

Carrier-mediated transport

movement of a substance across a membrane by means of a carrier molecule

Facilitated diffusion

moves substances from a higher to lower concentration; does not require ATP

Active transport

moves substances from a lower to higher concentration; requires ATP

Cystic fibrosis

genetic disorder that affects the active transport of Cl- into cells

Secondary active transport

moving concentration gradient to move another substance

Secondary active transport: Cotransport

same direction

Secondary active transport: Countertransport

opposite direction

Endocytosis

movement of materials into cells by formation of vesicles

Phagocytosis

cell eating; solid particles are ingested

Pinocytosis

cell drinking; smaller vesicles are formed and contains liquid

Exocytosis

secretion of materials from cells

Nuclear envelope

two-layered membrane that bounds the nucleus

Nuclear pores

where materials can can pass into or out the nucleus

Chromatin

loosely coiled chromosomes

Nucleoli

consists of ribosomal RNA and proteins

Ribosomes

Site of protein synthesis

Endoplasmic Reticulum

Forms tubules/sacs throughout the cell

Rough E.R.

protein synthesis and modification; contains ribosomes

Smooth E.R.

lipid synthesis, detoxification, and Ca storage

Golgi Apparatus

Modifies, packages, and distributes lipids and proteins

Secretory vesicles

Transports and stores materials within cells

Lysosomes

Membrane bound sacs containing hydrolytic enzymes

Peroxisomes

Enzymes that digest fatty acids and amino acids

Peroxisomes

Enzymes that catalyze the breakdown of hydrogen peroxide

Proteasomes

Not bound by membranes

Digest selected proteins

Mitochondria

Major site of ATP production

Cytoskeleton

Holds organelles in place; enables the cell to change shape

Microtubules

support the cytoplasm; assist in cell division

Microfilaments

involved in cell movement

Intermediate filaments

provide mechanical support

Centrosome

where microtubule formation occurs

Centrioles

specialized zone of the cytoplasm

Spindle fibers

involved in separation of chromosome during mitosis

Cilia

moves substances over the surface

Flagella

propel sperm cells

Microvilli

increase the surface area of cells; aids in absorption

Gene

sequence of nucleotides

Transcription

making a copy of a gene

Messenger RNA (mRNA)

the copy itself (Gene)

Codons

groups of three nucleotides

Translation

converting that copied information into a protein

Translation RNA (tRNA)

carry the amino acids

Anti-codon

series of three nucleotides of tRNA

Nucleotide Pairs: Cytosine

Guanine

Nucleotide Pairs:Thymine

Adenine

Nucleotide Pairs:Uracil

AdenineUAA

UAA

stop codon

Interphase

non-dividing phase

Cell Division

formation of daughter cells from a single parent cell

46 Chromosomes

diploid no. of chromosomes

2 X Chromosome

Female

X + Y Chromosome

Male

Prophase

chromatin condenses

Metaphase

chromosomes align at the center

Anaphase

chromatids separate at the centromere and migrate to opposite poles

Telophase

chromosomes unravel to become chromatin

Differentiation

Cells develop specialized structures and functions

Apoptosis

Programmed cell death

Cellular Aspects of Aging

1. Cellular clock. 2. Death genes. 3. DNA damage. 4. Free radicals. 5. Mitochondrial damage.

CELLS

Are the structural units of all living things, from one-celled organisms such as amoebas to complex multicellular organisms such as humans, animals, and plants.

4 concepts of the cell theory

· A cell is the basic structural and functional unit of living organisms.

· The activity of an organism depends on the collective activities of its cells.

· According to the principle of complementarity, the activities of cells are dictated by their structure (anatomy), which determines function (physiology).

· Continuity of life has a cellular basis.

The Nucleus

It is the “headquarters,” or the control center of all cells.

3 main regions or parts of cell

a nucleus, a plasma membrane, and the cytoplasm

Nuclear envelope

allows some but not all substances to pass through it, but substances pass through it much more freely than elsewhere because of its relatively large pores

Nuclear membrane

encloses a jellylike fluid called nucleoplasm in which other nuclear elements are suspended

Nucleoli

The nucleus contains one or more small, dark staining, essentially round bodies called

Chromatin

It is formed when a cell is not dividing, its DNA is carefully wound around proteins called histones to form a loose network of “beads on a string”.

Plasma Membrane

It is a fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment.

Plasma Membrane

consists of two phospholipid (fat) layers arranged “tail to tail,” with cholesterol and floating proteins scattered among them.

Fluid Mosaic Model

The proteins, some of which are free to move and bob in the lipid layer, form a constantly changing pattern or mosaic, hence the name of the model that describes the plasma membrane.

Glycoproteins

_________ in the glycocalyx act as an adhesive or cellular glue.

Cells are bound together in three ways

· Glycoproteins in the glycocalyx act as an adhesive or cellular glue.

· Wavy contours of the membranes of adjacent cells fit together in a tongue-and-groove fashion.

· Special cell membrane junctions are formed. These junctions vary structurally depending on their roles.

Tight junctions

are impermeable junctions that encircle the cells and bind them together into leakproof sheets.

Desmosomes

Are anchoring junctions scattered like rivets along the sides of adjacent cells.

Gap Junctions

communicating junctions. These junctions are commonly found in the heart and between embryonic cells.

Cytoplasm

is the cellular material outside the nucleus and inside the plasma membrane. It is the site of most cellular activities, it is the “factory floor” of the cell.

Cytosol

Is semi-transparent fluid that suspends the other elements. Dissolved in the cytosol, which is largely water, are nutrients and a variety of other solutes