Bio Chapter 3 The Living Unitys

Anatomy Chapter 3

Plasma Membrane

the outer boundary of the cell, acts as a selectively permeable barrier (arranged in bilayer)

Cytoplasm

the intracellular fluid packed with organelles, small structures that perform specific cell function

the cellular material between the plasma membrane and nucleus

Nucleus

an organelle that controls cellular activities. typically the nucleus lies near the cell’s center

Extracellular Fluid

dissolves and transports substances in the body

Cellular secretions

aid in digestion (intestinal and gastric fluids), acts as lubricants (saliva, mucus and serous fluid)

Extracellular matrix

a jellylike substance that acts like “cell glue” to bind body cells together.

Functions of the Plasma membrane

Physical barrier

seletive permeability

communication

cell recognition

The Fluuid Mosaic Model

The foundational framework used by biologists to describe the structure and behavior of cell membranes.

made up of proteins, phospholipids, cholesterol and carbs

Integral protein

embedded in the lipid bilayer with many spanning the entire membrane.

Peripheral proteins

not embedded in the bilayer, attached to integral proteins or anchored to the membrane

Glycocalyx

Fuzzy, sticky carbohydrate-rich layer on the cell surface (formed by glycoproteins and glycolipids. able to distinguish between friend and foe

Cell Junction

allow neighboring cells to adhere to each other, communicate, or aid'/inhibit the movement of the molecules between cells

3 types of cell junctions

Tight

Desmosomes

Gap

Tight Junction

formed by interlocking integral proteins in adjacent plasma membranes, creates a continuous seal around the cell.

Forms an impermeable barrier between cells.

prevents substances from passing through the extracellular space

Desmosomes

Anchoring junctions that act like molecular “velcro” to bind neighboring cells together into sheets

prevents cells from separating when subjected to pulling forces.

Gap Junction

cells are connected by hollow cylinders made of transmembrane proteins

allows communication between cells. permits passage of (ions, simple sugars, other small molecules)

2 ways substances move through the plasma membrane

Passive Transport

Active Transport

Passive transport

substances cross the membrane without energy input from the cell (ATP)

Diffusion (simple and facilitated)

Osmosis

Active Transport

the cell provides energy (ATP) to move substances across the membrane.

(primary and secondary)

Vesicular transport

2 types of facilitated diffusion through passive transport

Carrier-mediated facilitated diffusion

channel-mediated facilitated diffusion

Simple Diffusion

substances move directly through the lipad bilayer

movement of particles frfom an area of high concentration to low

no ATP required

Facilitated Diffusion

substances cannot pass through the lipid bilayer

requires membrane transport proteins

substances move through water-filled proteins channels

movement occurs down the concentration gradient

Carrier-mediated facilitated diffusion

transport molecules that are too large to pass through channels

carrier transmembrane proteins alers its shape to envelop and release substance

Channel-mediated facilitated diffusion

transports substances through aqueous (water-filled) channels from one side to the other.

leaked channels (always open)

gated channels (opened or closed by chemical or electrical signals)

Osmosis

movement of water trough a selectively permeable membrane. allows some substance to pass while excluding others.

Secondary Active Transport (Cotransport)

uses energy stored in ion concentration gradients created by primary active transport

2 types of secondaryh active transport

Symport & AntiportS

Symport

two transported substances move in the same directionS

Antiport

two substances cross the membrane in opposite directions

Vasicular Transport

uses vesicles (bubble-like membranous sacs and cellular energy to move large substances or large amounts of substances across the membrane

Types of Vesicular Transport

Endocytosis - in cell

(phagocytosis, pinocytosis, receptior-mediated endocytosis)

Exocytosis - out of cell

Endocytosis

movement of substances into the cell using vesticles.

outcomes include digestion by lysosomes, recycling of membrane components and transcytosis across the cell

Phagocytosis (cell eating)

the cell engulfs large particles or solid material

ex. macrophages/phagocytes1

Receptor-mediated endocytosis

highly selective receptor proteins bind to specific substances by bind to specific substances by binding them to specific receptors on the cell surface before engulfing them into vesicles

Exocytosis

materials are packaged into membrance-bound vesicles and transported out of the cell.

secrete chemical messengers like neurotransmitters

3 Major Elements of Cytoplasm

Cytosol, Inclusions, Organelles

Cytosol

viscous, semitransparent fluid suspending other cytoplasmic elements

mostly water but contain proteins, salts, sugars and other solutes

Inclusions

stored nutrients and cell products

not present in all cells

Organelles

metabolic machinery of the cell

each performs a specialized function

Ribosomes

small granules composed of proteins and ribosomal RNA.

site of protein synthesis

Endoplasmic Reticulum

extensive network of interconnected tubes & parallel sacs.

Rough and Smooth ER

Rough ER

Studded with ribosomes

package proteins into vesicles for transport to the Golgi

Smooth ER

Lacks ribosomes

Fat synthesis (lipid, cholesterol synthesis, phospholipid, steroid

Golgi Apparatus

stacks of flattened membranous sac

associated with many vesicles

function: modifies proteins and lipids from rough ER

packages meterials for transport

Lysomes

spherical membranous organelles, contains hydrolytic digestive enzymes

Function: digest materials taken in by endocytosis (destroys bacteria, viruses, and toxins)

Peroxisomes

small spherical membranous sacs, contains exidases and catalases

Function: detoxify harmful substances, convert hydrogen peroxide to water

Cytoskeleton

network of protein rods and accessory proteins within the cytosol

Function: supports cellular structures, maintains cell shape

Centrosome

located near nucleus, contains centroles

Centrioles

paired barrel-shaped structures arranged at right angles

organized the mitotic spindle during cell division

form bases of cilia and flagella

Cilia

whiplike, motile cellular extensions

move materials across the cell surface

doesnt move the cell itself

Flagella

Long projections, like a tail

mobilizes the cell

Microvilli

tiny fingerlike extensions of the plasma membrane the project from exposed cell surfaces.

Function: increase surface area for absorption.

(ex. intestinal cells, kidney tubule cells)

3 Main Components of nucleus

Nuclear Envelope

Nucleoli

Chromatin

Nuclear Envelope

Double membrane barrier surrounding the nucleus

acts as a barrier to protect the nucleus

Nuclear Pores

Openings within the nuclear envelope, lined by protein complexes, form aqueous transport channels.

Function: regulate movement in and out of nucleaus

allows export of RNA molecules

Allows import of proteins from the cytoplasm

Nucleolus (little nucleus)

Dark-staining spherical bodies within the nucleus, usually one or two per nucleus

Function: site of ribosomal subunit assembly

largest in actively growing cells producing large amounts of proteins

Chromatin

DNA and histone proteins

Function: stores and organizes genetic information

Chromosomes

when cells prepare to divide

Function: prevents DNA tangling and breaking during cell division

The Cell Cycle

The series of changes a cell undergoes from formation until reproduction.

2 Major periods of cell cycle

Interphase

Mitotic Phase

Interphase

Growth and Preparation, cells carry out metabolic activities and prepare for division. often called the growth phase.

3 sub-phases of Interphase

G1 - growth and protein synthesis

S (Synthesis) - DNA replication

G2 - prepares for mitosis

DNA Replication

Uncoiling

Separation

Assembly

Mitotic Phase

essential for growth, repair, replacement of worn-out cells

Phases of Mitosis (PMAT)

Prophase

Metaphase

Anaphase

Telophase

Prophase

Chromatin condenses into chromosomes

Nuclear envelope breaks downM

Metaphase

Chromosomes align in the middle of the cell

Anaphase

Sister chromatids separate & each chromatid becomes an individual

Telophase

Chromosomes reach opposite poles

Chromosomes uncoil into chromatins

New nuclear envelopes form

Cytokinesis

Division of the cytoplasm.

Contractile ring pinches the plasma membrane inward.

3 Types of RNA

Messnger RNA (mRNA)

Ribosomal RNA (rRNA)

Transfer RNA (tRNA)

Messenger RNA (mRNA)

Carries coded information from DNA to the cytoplasm

Ribosomal RNA (rRNA)

Combines with proteins to form ribosomes

Transfer RNA (tRNA)

Delivers amino acids to ribosomes, decodes mRNA instructions

2 Major steps of Protein Synthesis

Transcription - DNA information is encoded into mRNA

Translation - translate3s of the language of nucleic acids into the language of proteins (Codon & Anticodon)

Apoptosis (Programmed Cell Death)

controlled destruction of cells

Function: removes unnecessary cells

supports normal development

Protects tissues from damaged cells