Anatomy & Physiology

Chapter 3

Cells

Eukaryotic

Prokaryotic

Cell membrane

Thin, flexible, and somewhat elasticSelectively Permeable

Allows some things in/out but not others What are some things that are

selectively permeable?Signal Transduction

Helps signals from outer environment get into the cell

Cell Membrane Structure

Double layer of phospholipid molecules. The water soluble head (phosphate group) forms the surface. The insoluble tail (fatty acid chain) is inside the layers.

What types of particles could easily pass through (solubility)?

Cell MembraneFibrous proteins

Provide structure for the cell membrane, make it more rigid.

Globular proteins Called integral proteins/transport

proteins imbedded in the interior. They span the membrane channel

allowing small molecules inside (may be a pore)

Cytoplasm

The fluid that makes up the entire interior of the cell.

Organelles are suspended in it.Provides an area for reactions to

occur, supports the cell with osmotic pressure

Endoplasmic Reticulum

ER membrane is membrane-bound flattened sacs, elongated canals, and fluid filled vesicles.

Plays a role in protein and lipid synthesis.

Transports molecules throughout the cell.

Attachment site for ribosomes

Ribosomes

Found on the ER and floating in the cytoplasm

composed of protein and RNAWhat is it’s function?

Golgi Apparatus

Composed of a stack of 6 cisternaeRefines, packages, and delivers

proteins synthesized by the ribosomes

Why do think proteins would need refining?

Mitochondria

Elongated fluid filled sacMoves slowly through the cytoplasmReproduce by dividingContains small amounts of DNA Has an outer and inner membrane

layer.

Mitochondria

The enzymes and the mitochondria control many of the chemical reactions that release energy.

What are the molecules the mitochondria produce?

What are the substances mitochondria utilize to produce cellular energy?

Mitochondria

A typical cell will have about 1700 mitochondria.

What types of cells would have more mitochondria?

Lysosomes

The cell’s garbage disposal.Commonly appear as tiny

membranous sacs that contain powerful enzymes that break down protein, carbohydrates, and nucleic acids as well as foreign particles

They also destroy worn cellular parts.

Peroxisomes

The outer membrane of a peroxisome contains 40 enzymes that perform various duties: synthesis of bile acids breakdown of lipids degradation of rare biochemicals detoxification of alcohol

Cilia & Flagella

Cilia occur in large numbers on the surface of some epithelial cells.

Cilia are tiny hairlike structures Used to move substances along the

membraneFlagella are tail-like structures that aid in

cell motilityWhy would cells have cilia instead of

flagella?

Cytoskeleton

Microtubules Provide passage ways to transport

substances throughout the cell Similar to blood/lymphatic vessels in the

bodyMicrofilaments

Provide a framework of support for the cell

Similar to bones in the body

Nucleus

Directs the activities of the cell.Enclosed by a double-layered

nuclear envelope.Nuclear envelope consists of an

inner and outer lipid bilayer membrane.

Nucleolus

Small, dense body composed largely of RNA and protein.

No surrounding membrane.Site of ribosome production.Cells may have more than one

nucleolus.

Chromatin

Consists of loosely coiled fibers in the nuclear fluid

Stores DNA and Forms chromosomes during cell reproduction

Composed of DNA

Movement of substances

Diffusion Moves from high concentration to low. Osmosis – diffusion of water No energy needed

Facilitated Diffusion Big substance, still goes from high to low Uses proteins No energy needed

Active Transport

Movement of large particles by carrier proteins from low concentration to high concentration.

Does it require Energy? It may use as much as 40% of a

cell’s energy supply.

Active Transport

Active transport is similar to facilitated diffusion.

What’s the difference?Fig 3.16 page 62

Solute pumps

Transport amino acids and most ionsSodium-potassium pump

Essential for nerve impulses Why could transporting ions create an

electrical impulse?

Endocytosis & Exocytosis

Molecules or particles too large to pass through the membrane by diffusion are actively transported into (endocytosis) and out of (exocytosis) the cell.

Cellular Processes

The cell depends on proteins more than any other compound

For this reason the cell has it’s own method of creating proteins that it needs

Protein Synthesis Broken into two parts:

Transcription (DNA -> RNA) and Translation (RNA -> Protein)

Transcription

Producing a strand of messenger RNA (mRNA) from the DNA strand

mRNA uses one strand of DNA and is complementary to that DNA Except in RNA Uracil (U) takes the place of

Thymine (T)RNA polymerase moves along DNA

strand and adds nucleotides to mRNA strand

Transcription

Occurs in the nucleusWhen finished:

DNA winds back up mRNA is sent out of nucleus to be used

for translationmRNA now contains instructions on

how to build protein (codons)

Translation

Building the protein from the mRNA strandDone at the ribosomeCodons used to indentify amino acid

sequenceAll three types of RNA must come together

to build the protein rRNA prepares ribosome tRNA brings amino acid (contains

anticodon) mRNA brings the instructions

Translation

tRNA brings amino acid and binds to mRNA

Enzymes remove the amino acid from that tRNA and attach it to the growing chain

When complete: The A.A. chain is released from the

ribosome, folds and becomes a protein The mRNA and ribosome is reused to make

more of the same protein

Metabolism

What does metabolism mean to you?The sum/total of all chemical

reactions within the cell.There are two types of metabolic

reactions: Anabolism Catabolism What do you think each one means?

Anabolism

Where have you heard anabolic before?

Anabolism- larger molecules are constructed from smaller ones, requiring the input of energy

Anabolic metabolism provides all substances required for cellular growth and repair.

Catabolism

Process of breaking down larger molecules into smaller ones.

What will the breaking down of larger molecules do?

Provide Energy! An example of catabolic metabolism is

digestionWhat can be said about weight gain/loss

and the balance between catabolism and anabolism?

Metabolic Rates

Basal metabolic rate - the amount of energy expended when the body is at rest

BMR for an average adult (155 lbs) 60-72 Cal/hour What are factors that affect the BMR?

Surface area, Age, Gender, EmotionsTotal Metabolic Rate – Total calories the body

must consume to fuel activities Small increases in muscular activity causes large

jumps in TMR

EnzymesMetabolic reactions must be carefully controlled!

How are these controlled?ENZYMES!

Most reactions will not occur without them Enzymes are required in only small amounts

Why might this be?They are not used up during the reaction.

Does one enzyme control all reactions?No, enzymes only act on a particular rxn.

One that contains their substrate.

Enzymes

How does an enzyme recognize its substrate?

Shape – the way the enzyme is foldedThe enzyme then binds to the substrate

at the active site This is the action that causes the reaction

to occur and the cell to metabolize substances Example: lock and key

Cancer

Cells that divide uncontrollablyWhy?

Oncogene Tumor-suppressor gene

Oncogenes must be turned on while tumor-suppressor genes are turned off Mutations cause this to happen

Cancer

What are mutations caused by?Usually not caused by genetic errors a

person is born with. But you can be genetically more susceptible What does this mean?

Primary Cause - Carcinogens Radiation – from radioactive materials, UV, etc. Chemicals – Pollutants, tobacco, consumer

products

Stages of Cancer

Hyperplasia - first abnormal growth Excess of normal appearing cells

Dysplasia - cells begin to appear abnormalLocalized cancer - ball of abnormal cells and

blood nourishment A.K.A Tumor

Two types of Tumors Benign - will not spread to surrounding tissues Malignant – will spread to other tissue

Stages of Cancer

If Malignant:Invasion into adjacent tissueMetastasis - invasion of lymph and blood

vessels Leads to spreading to other parts of body

Let’s say colon cancer spreads to the lungs, what type of cancer is it?

Still considered colon cancer because it still shows same abnormalities and characteristics as original

Most common causes of death due to cancer

WomenLung 25%

Breast 17%

Colon/rectum 10%Leukemia/Lymphoma

8

Ovary 6

Pancreas 5

Uterus/cervix 5

Most common causes of death due to cancer

MenLung 32%

Prostate 14%

Colon/rectum 9%

Leukemia/Lymphoma

9%

Kidney/Bladder 5%

Pancreas 5%

Why is Cancer so serious

As a tumor gets larger, it will begin to grow its own blood supply

This steals nutrients and oxygen, eventually choking off surrounding tissues

Surrounding tissues then begin to fail

Treatment3 most commonSurgery

Ususally best option da Vinci surgical system

Radiation Internal and external Used to shrink tumor, usually combined with other

treatmentsChemotherapy-anticancer medicine

Targets all fast growing cells Delivered to all body tissues Problem?

Treatment

Vaccine - HPV (human papillomavirus) causes most cervical cancer cases

Hormone therapyGene therapy