biology mock quiz part 2

Cell

The ____ consists of both membrane-bound and non-membrane-

bound organelles.

Plasma membrane

is the cell’s primary barrier.

Mosaic

• The membrane is "______" because it is composed of different types of molecules (lipids, proteins, and carbohydrates).

Fluidity

The membrane is "fluid" due to its natural viscosity, meaning the components are not fixed in place but can move around

Kinks

These are found in the fatty acid tails of the phospholipids.

Cholesterol

• These molecules are embedded within the membrane and act as regulators of fluidity, ensuring the membrane doesn't become too loose or too rigid.

Lipid Bilayer

This is the core structure of the membrane.

Cytoplasm and Nucleus

are part of the Protoplasm

Phospholipids

These are the main building blocks. They have two distinct parts: a hydrophilic (water-loving) head that 

faces the watery environment outside and inside the cell, and hydrophobic (water-fearing) tails that are tucked inside, away from water.

Integral proteins

• These proteins are embedded deep within the lipid bilayer, often spanning across the entire membrane.

Peripheral proteins

These are located on the outer surface of the membrane rather than being buried inside it.

Glycolipids

Carbohydrates attached directly to lipids on the cell surface.

Glycoproteins

Carbohydrates attached to proteins. These are crucial for cell-to-cell recognition and communication.

Channel proteins

These act like a tunnel or a hollow pore. They 

provide a specific pathway that allows certain molecules to pass through the membrane without changing shape.

Carrier proteins

These function like a revolving door. The process is: Bind, Change shape, Flip, and Release. The protein grabs a specific molecule on one side, changes its shape to "flip" the molecule, and then releases it on the other side.

Cell recognition proteins

These proteins have carbohydrate chains attached to them (often called glycoproteins).

Their role is to act as an "ID tag" for the cell, allowing the immune system or other cells to recognize them as "self"

or identify them as foreign invaders.

Receptor proteins

These act like antennae or sensors on the surface of the cell. They have specific shapes that allow them to bind with chemical signals (like hormones or other messengers). When a molecule binds to the receptor, it triggers a

reaction or a specific activity inside the cell.

Cytoskeleton

is a network of protein fibers that provides the cell with its structural framework.

Microtubules

• Structure: Helically arranged globular proteins called tubulin; A microtubule is a helix of

ɑ-tubulin and β-tubulin subunits.

• Functions: They radiate from centrosomes and form spindle fibers used to move chromosomes during cell division.

Microfilaments

• Structure: Long fibers of actin protein; they are the thinnest cytoskeletal element.

• Functions: Facilitate cell and organelle movement and help change the cell's shape.

Intermediate filaments

• Functions: Provide structural integrity to the plasma membrane, help maintain cell shape, and anchor the nucleus in place.

Cytoplasm

is the space where all different subcellular structures are located.

Cell wall

is a rigid structure surrounding the cell membrane. It helps maintain cell shape and prevents the cell from bursting, especially when excess water is absorbed.

Bacterial cells

• Most have a cell wall made of peptidoglycan

Fungal cells

• Some have a cell wall consisting of chitin.

Plant cells

The cell wall consists of mesh-like cellulose fibers.

1.Cell membrane

2.Cytoplasm

3.Nucleus

Cell’s Three Major Divisions:

1.Plasma membrane

2.Cytoskeleton

3.Cytoplasm

4.Cell wall

Major Parts of the Cell: