UNIT 3 - Cells and Tissue Membranes

Anabolism

Build up of molecules: requires energy

Catabolism

Break down of molecules; releases energy

Cells

Basic unit of all living organisms, including human

Plasma membrane / Cell membrane

Thin outer covering of the cells

Controls entry and exit of substances

Nucleus

The control center of the cell

DNA within the nucleus regulates protein and therefore the chemical reactions of the cell

Cytoplasm

Supports organelles

Site of chemical reactions

Transports substances

Provides support

Ribosomes

Site of protein synthesis (translation)

Free Ribosomes

Ribosomes that are not to any other organisms

Rough Endoplasmic Reticulum

A flattened, sac-like membrane structures called cisternae

Synthesizes proteins and transports them to Golgi apparatus

Smooth Endoplasmic Reticulum

Manufactures lipids and carbohydrates

Detoxifies harmful chemicals

Stores calcium

Golgi Apparatus / Golgi Complex

Modifies, packages, and distributes proteins and lipids for secretion or internal use

Secretory Vesicles

Contains material produce in the cells

formed by the Golgi Apparatus

Secreted by exocytosis

Exocytosis

cells released/molecules exit from the cell to the outside

Endocytosis

Molecules go inside the cells

Lysosomes

Enzymes that digest material taken into the cell

Peroxisome

Serves one site of lipid and amino acid degradation

Breaks down hydrogen peroxide

Proteasomes

Break down proteins in cytoplasm (recycling machine)

Mitochondria

Site of aerobic respiration and the major site of ATP synthesis

Centrioles

Serves as centers for microtubule formation

Determines cell polarity during cell division

Form the basal bodies of cilia and flagellum

Cilia

Move substances over surfaces of certain cells

Flagellum

In humans, propels spermatozoa

Microvilli

Increase area of plasma membrane for absorption and secretion

Modified to form sensory receptor

Cell Metabolism and Energy Use

The chemical reactions that occur within cells

Synthesis of Molecules

Cells synthesize various types of molecules, including proteins, nucleic acids, and lipids

Communication

Cells produce and receive chemical and electrical signals that allow them to communicate with one another

Reproduction and Inheritance

Each cell contains a copy of the genetic information of the individual

Specialized cells (sperm and oocytes) transmit that genetic information to next generation

Light Microscope

Uses visible light and lenses to magnify and view

Electron Microscope

Uses a beam of electrons instead of light to produce a highly magnified image of very small objects

Scanning Electron Microscope (SEM)

3D model of the surface of the cell

Transmission Electron Microscope (TEM)

Shows the inside of a structure

Membrane Potential

The difference in electrical charge between the inside and the outside of the cell membrane

Glycolipids

Formed when carbohydrates combine with lipids

Glycoproteins

Formed when carbohydrates combine with proteins

Glycolyx

A carbohydrate-rich layer made of glycolipids, glycoproteins, and carbohydrates found on the outer surface of the plasma membrane

Phospholipid Bilayer

Phospholipids readily assemble to form a lipid bilayer, a double layer of phospholipid molecules

Polar heads

Water-loving (hydrophilic) parts of phospholipids

Non-polar heads

Water-fearing (hydrophobic) parts or a phospholipid

Cholesterol

The other major lipid

Limits the movement of phospholipids, providing stability to the plasma membrane

Integral Membrane Protein

Penetrates deeply into the lipid bilayer

Peripheral Membrane Protein

Attached to either the inner or outer surfaces of the lipid bilayer

Marker Molecules

Cell surface molecules that allow cells to identify other cells or other molecules

Attachment Protein

Integral proteins that allow cells to attach to other cells or extra cellular molecules

Cadherins

Keeps tissues organized and stable

Integrins

Help cells attach to other cells and the extracellular matrix

Transport Protein

Allows ions/molecules to move from one side of the plasma to the other

3 Characteristics of Transport Proteins

1.) Specificity - knows what to carry

2.) Saturation - limits the transport

3.) Competition - substances competing with eachother

Membrane Channels

Allows passive movement of specific ions of small molecules down their concentration/voltage gradients

Carbohydrate chains

Cell recognition , cell to cell adhesion, immune identification, and protection of the membrane surface

Cytoskeleton

Provides mechanical support, maintains cell shape, anchors membrane proteins, and helps with movement with endocytosis and exocytosis

Channel Proteins

One or more integral membrane proteins

Leak Channels

Allows ions to move through the membrane constantly

Gated Channels

Limits movement of ions by opening and closing

Ligand-gated

Opens/closes when chemical (ligand) binds to it

Voltage-gated

Closes/opens when the membrane voltage changes

Ligand

Generic term for any chemical signal made molecule used by cells to communicate with each other

Uniport

One substance transported

Symport

Two substances transported at the same direction

Antiport

Two sad stances transported in opposite directions

ATP-powered pumps

Transports proteins that use cellular energy to move ions/molecules across plasma membrane

Enzymes

Helps/speeds up chemical reactions in the cell

Plasma Membrane

Selectively permeable; allows only certain substances to enter

Passive Membrane Transport

1. Diffusion

2. Osmosis

3. Facilitated Diffusion

Diffusion

Random movement of molecules results in net movement from areas of higher to lower concentration

Osmosis (Passive membrane Transport)

Water diffuses across selectively permeable membrane

Facilitated diffusion

Substances move from high to low concentration

Has specificity, saturation, and competition

Secondary Active Transport

When a cell uses the energy stored in an ion gradient (usually Na⁺) to move another substance against its concentration gradient

Osmosis (Secondary Active Transport)

Diffusion of water (solvent) across a selectively permeable membrane, from a region of higher to lower water concentration

Concentration Gradient

Difference in concentration of a solute in a solvent between two points

Osmotic Pressure

The force required to prevent the movement of water across selectively permeable membrane

Phagocytosis

Cell-eating

The cell ingests large or solid particles

Pinocytosis

Cell-drinking

The cell takes in small particles or fluids from outside

DNA

Mostly found inside nucleus

Combines with proteins to form chromosomes

Contains information that directs protein synthesis, this process is called gene expression

Genes

Functional unit of heredity

Heredity

The transmission of genetic traits from parent to offspring

Gene Expression

The production of RNA/ proteins from the information stored in DNA

mRNA

Travels from nucleus to ribosomes in cytoplasm

tRNA

Carries amino acids to ribosomes

Cell Division

Formation of daughter cells from a single parent cell

Interphase (preparation)

Cell grows and carries out functions

Mitosis

Makes identical cells for growth and repair

Meiosis

Makes unique sex cells with half of DNA for reproduction

Prophase

Each chromosome is made up of two genetically identical strands of chromatin called chromatids, which are linked by centromere

Metaphase

The chromosomes align near the center of the cell

Anaphase

Chromatids separate, when this happens, each chromatid is then called a chromosome

Telaphase

Chromosomes in each of the daughter cells became organic to form separate nuclei

Tissue

Group of cells with similar structure and function + extracellular substances surrounding them

Histology

Study of tissues

Types of Tissues

1. Epithelial

2. Connective

3. Muscle

4. Nervous

Epithelial Tissue

Covers body surfaces, lines body cavities and organs, and forms glands

Epithelial Tissue Characteristics

1. Mostly composed of cells

2. Covers body surfaces

3. Distinct cell surfaces

4. Cell and matrix connections

5. Nonvascular

6. Capable of regeneration

Functions of Epithelial Tissue

1. Protects underlying structures

2. Acts as a barrier

3. Permits passage of substances

4. Secretes substances

5. Absorption of substances

Simple

One layer

Stratefied

More than one layer

Pseudostratifed

One later but looks like multiple

Squamous

Flat/scale-like

Cuboidal

Cube

Columnar

Column; taller than wide

Keratinized Stratified Squamous Epithelium

Outer layer of skin is compromised of a keratinized squamous layer

Non-keratinized Stratified Squamous Epithelium

Provides protection against abrasion and acts as a mechanical barrier

Transitional Epithelium

Special type of stratified epithelium that can be greatly stretched (e.g. urinary bladder)