Cell Specialization and Enzymes

Cell specialization

Cells are structured differently based on the job they do

Cell differentiation

The process of a cell changing from one type to another so it can perform a specific job

Stem cell

A blank cell that does not have a job yet and can become specialized

How a stem cell specializes

It divides into two daughter cells; one is a copy of the stem cell, the other keeps dividing until it becomes specialized

Why cell differentiation is important

It allows the body to make all the cell types it needs to move, breathe, remove wastes and respond to stimuli

Cells of the same type working together form a…

Tissue

Skeletal muscle cell

Long, elastic fibers with thousands of mitochondria; help muscles contract for movement

Mitochondrion

Organelle that helps produce energy for the cell

Why muscle cells have many mitochondria

They use a lot of energy to help the body move

Neuron (nerve cell)

Has a long axon and dendrites to conduct electrical signals in the body

Dendrites

Appendages of a neuron that send and receive signals from surrounding cells

Cardiac cell

Connected by intercalated discs so the cells coordinate contraction in a wave-like pattern

Smooth muscle cell

Contracts more slowly than skeletal muscle and can contract for a longer period of time

Red blood cell

Has increased surface area to efficiently transport oxygen

Osteocyte

Bone cell in the bone matrix; the sensing system of mature bone

Rod cell

Elongated cell in the retina of the eye; photoreceptor that helps you see

Fat cell

Has a fat reservoir to store lipids (triglycerides) as fuel for later

Immune cells

Come in a variety of structures to protect the body against pathogens such as bacteria and viruses

Enzyme

A specialized biological protein that speeds up chemical reactions by lowering the energy needed to start them

What do enzymes do to activation energy?

Lower it

Are enzymes used up in a reaction?

No; they stay unchanged and can repeat the job

Active site

The special spot on an enzyme with a unique shape where the substrate binds

Substrate

The target molecule that plugs into the enzyme's active site

Product

The new molecule formed after the enzyme changes the substrate

Lock and key model

The substrate fits the active site like a key fits a lock

Induced fit model

The enzyme hugs or adjusts its shape tightly around the substrate

Steps of enzyme action

Substrate binds active site; enzyme strains or joins bonds; substrate becomes product; product is released and enzyme is unchanged

What type of macromolecule is an enzyme?

Protein

Why does extreme heat stop an enzyme from working?

It changes (denatures) the shape of the active site so the substrate no longer fits

Why must enzymes be specific?

Each enzyme's active site has a unique shape that fits only certain substrates