A&P: Chapter 3, 4 and 5

3 parts of the cell

1. Plasma/cell membrane

2. Cytoplasm

   -cytosol

   -organelles

3. nucleus

Plasma membrane

forms the cell’s flexible outer surface, separating the cell’s internal environment to the external environment. It is a selective barrier that regulates the flow of materials into and out of a cell.

Cytoplasm

consists of all the cellular contents between the plasma membrane and the nucleus.

cytosol

the fluid portion of cytoplasm, also called intracellular fluid, contains water, dissolved solutes and suspended particles.

Organelles

within cytosol, each organelle has a characteristic shape and a specific function. examples: cytoskeleton, ribosomes, endoplasmic reticulum, golgi complex, lysosomes, peroxisomes, and mitochondria.

nucleus

large organelle that houses most of cell’s dna. within the nucleus, each chromosome (a single molecule of DNA associated with several proteins, contains thousands of hereditary units called genes.

genes

control most aspects of cellular structure and function

Plasma membrane

flexible (yet sturdy) barrier that surrounds and contains the cytoplasm of a cell.

Structure of the plasma membrane

the lipid bilayer

the lipid bilayer

The basic structural framework of the plasma membrane. have 2 back to back layers made up of three types of lipid molecules- phospholipids, cholesterol, and glycolipids.

phospholipids

lipids that contain phosphorus

Cholesterol

a steroid with an attached hydroxyl group (-OH)

glycolipids

lipids with attached carbohydrate groups

amphipathic

a molecule that have both polar and nonpolar parts

glycoproteins

proteins with carbohydrate groups attached to the ends that protrude into the extracellular fluid

ion channels

formed by some integral proteins, they are pores or holes that specific ions can flow through to get in or out of the cell. most ion channels are selective: only allow a single type of ion to pass through

carriers

some integral proteins are this and they selectively move a polar substance or ion from one side of the cell membrane to the other. also known as transporters

receptors

integral protein that serve as a cellular recognition site. each type of receptor recognizes and binds a specific type of molecule.

linkers

integral proteins that anchor proteins in the plasma membranes of neighboring cells to one another or to protein filaments inside and outside of the cell.

permable

a structure permits the passage of substances through it

impermeable

the structure does not permit passage of substance through it

selectively permeable

plasma membrane permits some substances to pass more readily than others

lipid bilayer

portion of the plasma membrane that is highly permeable to nonpolar molecules and moderately permeable to small, uncharged polar molecules, and impermeable to ions and large uncharged polar molecules.

Concentration gradient

difference in the concentration of a chemical from one place to another, such as from the inside to the outside of the plasma membrane

electrical gradient

difference in electrical charges between two regions

why is the electrical gradient and concentration gradient important?

they help move substances across the plasma membrane

passive transport

a substance that moves down its concentration or electrical gradient to cross the membrane using only its own kinetic energy

Active transport

cellular energy is used to drive the substance “uphill” against its concentration or electrical gradient. this cellular energy is ATP

diffusion

passive process in which the random mixing of particles in a solution occurs because the particle’s kinetic energy

Osmosis

type of diffusion where there is a the net movement of a solvent through a selectively permeable membrane. is a passive process/transport. solvent is water, which moves across a plasma membrane from area of high water concentration to an area of low water concentration.

Isotonic solutions

red blood cells maintain their normal shape

hypotonic solutions

red blood cells undergo hemolysis (destruction of red blood cells)

Hypertonic solution

red blood cells undergo crenation (the formation of notches around the cell due to loss of water)

What is diffusion important for

-gas exchange

-some nutrients

-excretion of some wastes

examples: respiratory gases, some lipids, small alcohols, ammonia.

Facilitated diffusion

Solutes that are too polar or highly charged to move through the lipid bilayer by simple diffusion can cross the plasma membrane by a passive process called ___.

examples: glucose, fructose, urea, some vitamins

Transport in vesicles

substances are transported in vesicles from one structure to another within a cell.

Endocytosis

cellular process when materials move into a cell in a vesicle formed from the plasma membrane (require ATP)

exocytosis

cellular process where materials move out of a cell by the fusion with the plasma membrane of vesicles formed into the cell. (require ATP)

cytoskeleton

a network of three types of protein filaments: microfilaments, intermediate filaments and microtubules that extend throughout the cytoplasm.

Functions: serves as a scaffold that helps determine a cell’s shape and organize the cellular contents

Aids movement of organelles within the cell, of chromosomes during cell division, and of whole cells such as phagocytes.

Centromes

also know as the microtubule organizing center, located near the nucleus, consists of two components: a pair of centrioles and the pericentriolar matrix.

• dense areas of the cytoplasm

• contain centrioles

  -paired

  -right angles

  -organize the microtubules and the spindles during mitosis

Pericentriolar matrix or (function of centrosomes)

contains tubulins which are used for growth of the mitotic spindle and microtubule formation

microtubules

are the dominant components of cilia and flagella, which are motile projections of the cell surface

cilia

are numerous, short, hairlike projections that extend from the surface of the cell.

-each one contains 30 microtubules surrounded by plasma membrane

Function: moves fluids along a cell’s surface

flagellum

similar in structure to cilia but are typically much longer.

Function: moves an entire cell.

It generates forward motion along its axis by rapidly wiggling in a wavelike pattern.

Ribosomes

are sites of protein synthesis

contains ribosomal RNA (rRNA)

is free standing or in clusters

on the endoplasmic reticulum

ribosomes synthesize proteins destined for specific organelles, for insertion in the plasma membrane or for export from the cell.

free ribosomes synthesize proteins used in the cytosol.

located in the mitochondria, where they synthesize mitochondrial proteins

endoplasmic reticulum

network of membranes in the form of flattened sacs or tubules.

the ER extends from the nuclear envelop (membrane around the nucleus) to which it is connected and projects throughout the cytoplasm.

there are two forms of ER (smooth and rough)

Rough endoplasmic reticulum

outer surface is studded with ribosomes, sites of protein synthesis.

synthesizes glycoproteins and phospholipids that are transferred into cellular organelles, inserted into the plasma membrane or secreted during exocytosis.

• originates from the outer membrane of nuclear envelop

• extends to cytoplasm

• rough due to ribosomes

• proteins are synthesized and shunted into the ER for packaging and transport

• first step in secretory pathway

Smooth endoplasmic reticulum

is a closed tubular network

has no ribosomes

functions: nutrient processing, synthesis and storage of lipids, detoxify certain drugs.

Golgi apparatus

-consists of 3 to 20 saccules (small, flattened membranous sacs with bulging edges).

Functions: modifies, sorts, packages, and transports proteins received from the rough ER

Forms secretory vesicles that discharge processed proteins via exocytosis into extracellular fluid; forms membrane vesicles that ferry new molecules to the plasma membrane; forms transport vesicles that carry molecules to other organelles such as lysosomes.

Vesicles

-lysosomes

-perioxosomes

-proteosomes

lysosomes

membrane enclosed vesicles that form from the golgi complex

contain powerful digestive hydrolytic enzymes that can break down a variety of molecules.

lysosomal membrane also includes transporters that move final products of digestion, such as glucose, fatty acids, and amino acids into the cytosol.

Functions:

-digest substances that enter a cell via endocytosis and transport final products of digestion into cytosol

-carry out autophagy, the digestion of worn out organelles

-implement autolysis, the digestion of an entire cell

-accomplish extracellular digestion

perioxisomes

similar but smaller thank lysosomes:

also called microbodies, contain several oxidases, enzymes that can oxidize (remove hydrogen atoms from) various organic substances.

proteasomes

destruction of unneeded, damaged or faulty proteins is the function of tiny barrel-shaped structures consisting of four stacked rings of proteins around a central core called __

mitochondria

referred to the powerhouse of the cell because they generate the most ATP

-site of ATP production

-double layered membrane

-they specialize in aerobic respiration: process of cellular respiration that takes place in the presence of oxygen to produce energy from food.

-generate ATP through reactions of aerobic cellular respiration

-play an important role in apoptosis (genetically programmed death of a cell)

Nucleus

most cells have a single nucleus, surrounded by a nuclear envelope

nuclear envelope separates nucleus from the cytoplasm

nucleoli: spherical bodies inside the nucleus, produce ribosomes

contains genes

-arranged along chromosomes made up of DNA

humans: 46 chromosomes in 23 pairs

functions: controls cellular structure

directs cellular activities

produces ribosomes in nucleoli

gene expression

a gene’s dna is used as a template for synthesis of a specific protein

first process of gene expression

transcription

transcription

the information encoded in a specific reigon of DNA is transcribed (copied) to produce a specific molecule of RNA

the synthesis of RNA molecules using DNA strands as templates so that genetic information can be transferred from DNA to RNA

the second process of gene expression

translation

translation

the RNA attaches to a ribosome, where the information contained in RNA is translated into a corresponding sequence of amino acids to form a new protein molecule.

Histology

the science that deals with the study of tissues

types of tissues

epithelial tissue

connective tissue

muscle tissue

nervous tissue

cell division

the process by which cells reproduce themselves

types of cell division: somatic cell division and reproduction cell division

somatic cell

is any cell of the body other than a germ cell

germ cell

a gamete (sperm or oocyte) or any precursor cell destined to become a gamete

somatic cell division

a cell undergoes a nuclear division called mitosis and a cytoplasmic division called cytokinesis, to produce two genetically identical cells, each with the same number and kind of chromosomes as the original cell

somatic cell division replaces dead or injured cells and adds new ones during tissue growth.

reproductive cell division

the mechanism that produces gametes, the cells needed to form the next generation of sexually reproducing organisms.

process consists of a special two step division called meiosis, in which the number of chromosomes in the nucleus is reduced by half

cell cycle

orderly sequence of events in which a somatic cell duplicates its contents and divides in two

interphase

the cell replicates its DNA through a process. consists of 3 phases: G1, S, and G2. S- stands for synthesis of DNA. G phases are periods when there’s. no activity related to DNA replication, they are thought a gaps.

g1 Phase

the interval between the mitotic phase and the s phase.

during G1, the cell is metabolically active; it replicates most of its organelles and cytosolic components but not its DNA. Replication of centrosomes also begins in G1 phase

lasts 8-10 hours

S phase

interval between g1 and g2

lasts 8 hours

DNA replication occurs. As a result of dna replication, the two identical cells formed during cell division later in the cell cycle will have the same genetic material.

G2 phase

interval between s phase and mitotic phase

lasts 4 to 6 hours

enzymes and other proteins are synthesized in preparation for cell division and replication of centrosomes is completed.

mitotic phase

results in the formation of 2 identical cells, consists of nuclear division and a cytoplasmic division to form two identical cells.

stages of mitosis

1. prophase

2. metaphase

3. anaphase

4. telophase

prophase

the chromatin fibers condense and shorten into chromosomes.

condensation process may prevent entangling of the long DNA strands as they move during mitosis

as microtubules lengthen they push the centrosomes to the poles (ends) of the cell so that the spindle extends from pole to pole.

mitotic spindle is responsible for the separation of chromatids to opposite poles.

then, nucleus disappears and the nuclear envelope breaks down

metaphase

microtubules of the mitotic spindle align the centromeres of the chromatid pairs at the exact center of the mitotic spindle.

anaphase

the centromeres split, separating the two members of each chromatid pair, which move towards opposite poles of the cell. one separated, the chromatids are termed chromosomes.

as chromosomes are pulled by microtubules of the mitotic spindle during anaphase, they appear v-shaoed because the centromeres lead the way, dragging the tailing arms of the chromosomes toward the pole.

telophase

final stage of mitosis, begins after chromosomal movement stops.

identical set of chromosomal, now at the opposite poles of the cell, uncoil and revert to the threadlike chromatin form. a nuclear envelope forms around each chromatin mass, nucleoli reappear in the identical nuclei, and the mitotic spindle breaks up

cytokinesis

division of cell’s cytoplasm and organelles into two identical cells

cytoplasmic division; in separate and equal proportions

epithelial tissue

covers body surfaces and lines hollow organs, body cavities and ducts; it also forms glands. this tissue allows the body to interact with both its internal and external environments.

arranged in continuous sheets in either single or multiple layers

avascular (has no blood vessels/ blood supply)

has a nerve supply

high mitotic rate

cells are closely packed and are held tightly together by many cell junctions.

classification of epithelial tissues

shapes and layers

shapes:

-squamous, cuboidal, columnar, and transitional

layers:

-simple, stratified, pseudostratified

simple epithelium

a single layer of cells that functions in diffusion, osmosis, filtration, secretion or absorption.

pseudostratified epithelium

appears to have multiple layers of cells because the cell nuclei lie at different levels and not all cells reach the apical surface.

stratified epithelium

consists of two or more layers of cells that protect underlying tissues in locations where there is considerable wear and tear

squamous cells

are thin, which allows for the rapid passage of substances through them

cuboidal cells

are as tall as they are wide and are shaped like cubes or hexagons.

may have microvilli at their apical surface and function in either secretion or absorption

columnar cells

much taller than they are wide, like columns, and protect underlying tissues.

their apical surfaces may have cilia or microvilli, and they often specialized for secretion and absorption

transitional cells

change shape, from squamous to cuboidal and back as organs of the urinary system such as the urinary bladder stretch (distend) to a larger size and then collapse to a smaller size

simple squamous epithelium

is a single layer of flat cells that resembles a tiled floor; centrally located nucleus is flattened and oval or spherical in shape

function: diffusion and filtration

present at sites of filtration (such as blood filtration in kidneys) or diffusion (such as diffusion of oxygen into blood vessels of lungs) and at sites of secretion in serous membranes.

found in parts of the body that are subject to little wear and tear or no mechanical stress

basement membrane

a thin extracellular layer that commonly consists of two layers, the basal lamina and reticular lamina.

basal lamina: closer to- and secreted by- the epithelial cells

separate tissues and protect them from mechanical stress

simple cuboidal epithelium

a single layer of cube-shaped cells; round, centrally located nucleus.

functions: secretion and absorption

found in ovaries and kidneys

simple columnar epithelium

two forms: nonciliated simple columnar and ciliated simple columnar

nonciliated simple columnar epithelium

a single layer of noncilitated columnlike cells with oval nuclei near base of cells. contains columnar epithelial cells with microvilli at surface and goblet cells.

-contain microvilli

-contain goblet cells that secrete mucous

-in intestines

functions: secretion and absorptions

microbilli

fingerlike cytoplasmic projections

ciliated simple columnar

a single layer of ciliated columnlike cells with oval nuclei near base of cells.

function: in the respiratory tract, the cilia beat in unison, moving mucus and foreign particles toward throat, where they can be coughed up and spit out.

helps move fluids and particles along surface

in trachea

motile

cilia

stratified epithelium

more durable and protective

basal cells replicate by mitosis and ultimately work their way to the surface

stratified squamous epithelium

found in the mouth and on the skin

functions in lubrication and protection

protection against abrasion, water loss, ultraviolet radiation, and foreign invasion.

has 2 or more layers of cells

stratified cuboidal epithelium

in mammary and sweat glands

functions in secretion and absorption

stratified columnar epithelium

functions in support and some movement

found in male urethra and vas deferens

transitional epithelium

several layers of cells

appearance is variable

capable of stretching

-permits distention of an organ

-lines the urinary bladder and portions of the ureters and urethra.