Biology Chapter 5 + 6

Walking Units of Life

Cell

smallest basic unit of life

comprised of organelles

Cell membrane

Separates cell from environment around it and helps regulate homeostasis

Phospholipid Bilayer

Composed of tightly packed phospholipids that controls what can go in or out of the cell

Characteristics of Phospholipid Bilayer

Center is hydrophobic while the phosphate heads on the outside are hydrophilic.

What can go through the phospholipid bilayer? Why?

Substances that are small and nonpolar (not electrically charged)

The phospholipids are tightly packed so large items can not pass, and the hydrophobic center rejects anything with a large charge.

What is an example of a substance that can pass through? Can not?

Oxygen and carbon dioxide are small and nonpolar so they can. Water is a large molecule and polar so it may not.

ex: Oxygen crosses 5 membranes from high concentration in lungs to low concentration into our bloodstream.

Is the phospholipid bilayer mobile?

Yes! It is fluid and moves from side to side.

amphipathic

Consisting of both hydrophilic and hydrophobic parts

How do plant cells stabilize the cell membrane?

Plants have a cell wall around the membrane which “boxes” it in

What are the 2 ways animal cells stabilize the cell membrane?

Animal cells can use sticky substances to glue the phospholipids together, thus stabilizing the membrane. ex: cholesterol

They can also anchor down the cell membrane to the ECM (extra cellular matrix) or to internal membranes.

How does a polar/large molecule enter the bilayer?

By installing pathways

ex: aquaporin

Aquaporin

Any protein that allows water transfer into the cell

How do we describe the way the cell membrane is designed?

The Fluid Mosaic Model

What are the three major types of cell?

Bacterial, Plant and Animal Cells

What type of cell is the smallest?

Bacterial Cell

Prokaryote

Primitive cell with no nucleus ex: bacteria cell

Eukaryote

Cell with a nucleus ex: plant and animal cell

Organelle

specialized structure within a cell

Nucleus

holds chromosomal DNA within cell and controls cell activity

Ribosomes

Site of protein synthesis

Lysosomes

ONLY FOUND IN ANIMAL CELLS

contains proteins capable of breaking down macromolecules (proteins, lipids, carbohydrates, and nucleic acids)

Mitochondria

site of cellular respiration and energy production (ATP)

Cytoplasm

gelatinous substance inside cell that holds organelles in place and facilitates movement

Vacuole

store water, nutrients, and waste in cell

-much larger in plant cells

Cell Wall

ONLY FOUND IN PLANT CELLS

gives cell structure

Chloroplasts

ONLY FOUND IN PLANT CELLS

produce energy through photosynthesis

Rough Endoplasmic Reticulum

network of membranes inside a cell that houses ribosomes

Smooth Endoplasmic Reticulum

network of membranes inside a cell that produce the lipids found in the cell membrane and detoxifies poisons (ex: growing tolerance of alcohol)

Golgi Apparatus

Transport + modifies vesicles

Vesicle

small spheres of membrane used for transport

Endoskeleton Membrane System

internal membrane system of the cell where the endoplasmic reticulum packages vesicles (lysosomes) that are then transported to the golgi apparatus. The golgi apparatus then modifies vesicles and sends them out of the cell, or to other places within it.

Bulk Transport

Movement of macromolecules into or out of the cell

Types of Bulk Transport

Endocytosis and Exocytosis

Endocytosis

Process where macromolecules are let into the cell

Exocytosis

Process where matter is forced out of the cell

ex: pancreatic cells make insulin but don’t use it, so the insulin and forced out and transferred to other places within the cell

Hypotonic Solution

Solution with a lower concentration of solutes

Hypertonic Solution

Solution with a higher concentration of solutes

Isotonic Solution

Solution has an equal concentration of solute