The Biology of Anatomy

A review of science past…

The Light Microscope• Total Power

Magnification: Eyepiece power multiplied by the Objective power.

• Usually there are 3 objective powers:

• Low: 4x magnification• Medium: 10x

magnification • High: 40x magnification

Plasma Membrane• The Plasma Membrane & Cell Membrane are

the same thing!• In an Animal Cell, it is the boundary between

the inside and outside of the cell.• It is crucial in maintaining the cell’s

homeostasis!!• It is selectively permeable, meaning it is

choosy about what enters and leaves the cell.• It keeps nutrients in, and harmful substances

out

Structure of the Plasma Membrane• The plasma membrane is a

Phospholipid Bilayer (Phospholipid = Fat,

Bilayer = 2 layers) and has protein embedded in it.

• Remember, lipids do NOT dissolve in water, so that is why cells stay together in your body that is full of water!

The round structures with tails are the Lipids.The big blue structure is the Protein.

More on the Phospholipids…• The “heads” are

hydrophilic (polar) and are attracted to the water inside and outside of the cell.

• The “tails” are hydrophobic (non polar) and do NOT like the water. The tails point to the middle of the plasma membrane.

So how do things get in & out??• Small things are able to

squeeze through the phospholipid bilayer and do not cost the cell any energy.

• Large things must be pumped into the cell through one of the large proteins and this costs the cell energy!

The General Animal Cell

Organelles & Functions• Nucleus: Controls the cells activities and holds

DNA. (Mayor)

• Plasma Membrane: Flexible boundary that controls what enters and leaves a cell.

(Bouncer)

• Mitochondria: Provide power/energy to the cell and is the site of cellular respiration.

(Power

Plant)

Endoplasmic Reticulum: Serves as the protein transport system of the cell.

Smooth E.R.: Has no ribosomes.Rough E.R.: Has ribosomes.

• Ribosomes: Site of protein synthesis.

(Factory)

Golgi Body: Modify, package, and sort cellular materials.

• Centrioles: Helps animal cells divide.

• Cytoskeleton: Gives structure to cytoplasm. Made of microfilaments (solid) and microtubules (hollow).

Cytoplasm: The clear fluid of the cell between the nucleus and cell membrane.

(Swimming Pool)

Lysosomes: Contains digestive enzymes that break down cellular waste.

Stem Cells

• All cells start out as a general, unspecialized cell that has the ability to become specialized according to it’s specific function.

• Here are some examples of specialized cells in the human body:

Specialized Cells of the Human Body

Red Blood Cells

Nerve Cell (Neuron)

Female Egg

Sperm Cell

DNA• Stands for Deoxyribonucleic Acid• Can’t leave the nucleus• Holds our genetic information (the way we look!)• Holds instructions for making

protein– Enzymes are a protein (remember

that?)– Enzymes are involved in all actions:

eating, thinking, running!

The Structure of DNA• DNA is a polymer• A Nucleotide is the monomer

that makes up the polymer DNA.

• So, several nucleotides (monomer) joined together make up DNA (polymer).

Base Pairing• Bases pair up and are held together

by a hydrogen bond.• Adenine always pairs with Thymine• Guanine always pairs with

Cytosine.• These make up the “steps” of the

“ladder”.• Everyone has errors or mutations

in their DNA, some are minor and have no impact while others can give rise to major disease and illness.

RNA• RNA stands for Ribonucleic Acid.• Main function is to make protein.• Found in the nucleus & cytoplasm• Made of nucleotides just like DNA but

with a few differences:– The sugar is Ribose, instead of

Deoxyribose.– It is single stranded– Uses the nitrogen base Uracil in place of

Thymine

Transcription• Occurs in the nucleus• The process begins with the DNA unzipping.• Single-stranded messenger RNA (mRNA) is

made by base pairing. The mRNA is a copy of the DNA (replacing T with U).

• The mRNA then separates from the DNA and the DNA zips back up.

• The mRNA leaves the nucleus and goes to a ribosome in the cytoplasm.

Translation• Occurs at the ribosome• mRNA is read by the ribosome 3 bases at a time.– These 3 bases are called a codon.– Each codon on the mRNA CODES for an amino acid.

• Translation begins when the ribosome finds the codon AUG (Start Codon)

• Transfer RNA (tRNA) brings amino acids to the ribosome.

• Translation stops when the ribosome reads a STOP codon (there are 3 stop codons).

• Amino acids at the ribosome link together by a peptide bond to form a protein!

“Hey, tRNA! I gotta code for an amino

acid, here! Why don’t you go fetch it for me!”

GGCGlycine

“Terrell” tRNA

AminoAcid

“Ref”Ribosome

Nucleus

mRNAtRNA

AminoAcid

Ribosome

mRNA Start codon

Growing polypeptide chain A.K.A. PROTEIN!!!!

Ribosome

tRNA

mRNA

tRNAAmino Acid

mRNARibosome Translation direction

Cell Division• Cells divide to make MORE of themselves by

the process of MITOSIS if it’s a body (somatic) cell.

• Cancer is uncontrolled cell growth.

Cell Division• Sex cells (gametes) do a process called

meiosis.• It looks similar to mitosis, except there is an

extra division and the end result are cells with HALF the number of chromosomes.