[ Gen Bio ] Lesson 2: Major Parts of the Cell

Cell membrane or plasma membrane

is the cell's primary barrier.

Cell membrane or plasma membrane

separates the cytoplasm from the external environment.

• phospholipids

• cholesterol

• membrane proteins

• glycolipids

• glycoproteins

Cell membrane or plasma membrane comprises the (5):

Head region / Hydrophilic Head Tail region / Hydrophilic Tail

phospholipids consists of 2 regions:

• phosphate group • hydrophilic

Head Region (2):

• two fatty acid chains • hydrophobic

Tail Region (2):

Hydrophilic

having a tendency to mix with, dissolve in, or be wetted by water.

(Heads up: know the Differences between Hydrophilic and Hydrophobic)

Hydrophobic

Water fearing; a property of molecules that do not mix with water

(Heads up: know the Differences between Hydrophilic and Hydrophobic)

Phospolipids

Consists of Hydrophilic head and Hydrophobic tail

Phospolipids

make up the phospholipid bilayer.

Phosphate heads Fatty acid tails

two phospholipid layers

Phosphate heads

face the cytoplasm and the cell's exterior.

Fatty acid tails

are sandwiched.

fluid mosaic model

describes the membrane structure.

Mosaic

different molecules such as proteins, sugars, and cholesterol

Fluidity

due to its natural viscosity

Kinks Cholesterol

Membrane fluidity is determined by: (2)

Kinks

in the fatty acid tails of the phospholipids

Cholesterol

molecules which act as regulators of fluidity

Selective permeability

is an important property of the "lipid bilayer", in which it only allows certain molecules to move into and out of the cell.

Permeable

Liquids, Alcohol, Small molecules (oxygen, nitrogen, carbon dioxide, water)

Impermeable

Polar molecules, Large molecules (glucose, amino acids, nucleic acids, proteins)

Channel Proteins Carrier Proteins Cell Recognition Proteins Receptor Proteins

Kinds of Membrane Proteins (4):

Channel Proteins

passageway of certain molecules

Carrier Proteins

change conformation to transport molecules

Cell Recognition Proteins

detect invading pathogens

Receptor Proteins

binding of molecules to trigger responses

Cytoskeleton

This consists of a network of protein fibers that gives the cell its structural framework.

Microtubules

These consist of helically arranged globular proteins called "tubulin."

Microtubules

It radiate from the "centrosomes"

Microtubules

Form spindle fibers that move chromosomes

Microfilaments

They consist of long fibers of "actin" protein, making them the thinnest cytoskeleton.

microtubules, microfilaments, intermediate filaments

Cytoskeleton consists of (3):

Microfilaments

They help facilitate cell and organelle movement.

Microfilaments

They can help change the shape of the cell.

Intermediate Filaments

Helps maintain cell shape; Anchors the nucleus

Cytoplasm

This is where all different subcellular structures are suspended.

Cytoplasm

It is composed of the "cytosol."

Cell Wall

is a rigid structure that surrounds the cell membrane.

Cell Wall

It helps maintain the shape of cells and prevent them from bursting.

Peptidoglycan

Most bacteria have cell wall made up of _______.

Chitin

The cell wall in some fungi consists of _____.

Cellulose Fibers

In plant cells, the cell wall consists of mesh-like ________.

Plasma Membrane Cytoplasm Cytoskeleton Cell Wall

4 Major Parts of the Cell