Intracellular Components

Ribosome

A molecule composed of ribosomal RNA and proteins located on the endoplasmic reticulum. Responsible for mediating protein synthesis

Golgi Apparatus

A membrane-bound organelle found near the cell nucleus in Eukaryotic cells. Responsible for sorting and packaging proteins for secretion to various destinations in the cell.

Organelle

A membrane-bound sub-cellular structure found in Eukaryotic cells. The Cell nucleus, mitochondria, ER, and Golgi apparatus are all examples

Cytoplasm

A fluid found in the main compartment of Eukaryotic cells. Includes everything outside the cell nucleus but the organelles and the cytoskeleton. The main components is cytosol

Nucleus

A large, double membrane-bound organelle found in Eukaryotic cells. Contain DNA and RNA

Lysosome

A membrane-bound organelle found in Eukaryotic cells. Contain acids and enzymes that degrade unwanted molecules.

Endoplasmic Reticulum

A membrane-bound organelle found in Eukaryotic cells. Makes direct contact with the cell nucleus and, since it is dotted with ribosomes, is the site of lipid and protein synthesis. Comes in two forms, smooth and rough

Endosome

A membrane-bound organelle found in Eukaryotic cells. Responsible for delivering molecules to the lysosome for digestion

Centrosome

A region of the cell near the nucleus from which microtubules sprout. Centrosomes are not found in all cells. Centrosomes are compromised of two centrioles

Centromere

A round structure that holds together sister chromatids

Peroxisome

A small, membrane-bound organelle found in Eukaryotic cells. Contains oxidizing enzymes that oxidize organic molecules and process hydrogen peroxide in the cell.

Chromosome

A structure composed of DNA and proteins containing all the genetic material of a cell. Found in the cell nucleus.

Cystoskeleton

A system of protein filaments found throughout the cytoplasm of Eukaryotic cells that help provide for cell structure. Composed of actin, Intermediate filaments and microtubules

Actin

A very abundant protein in Eukaryotic cells that is the main component of actin filaments

Mitochondria

An organelle within the cell. Much of cell respiration is carried out within its bounds

Eukaryote

An organism composed of one or more cells with defined intracellular components including a nucleus and cytosol. Includes all organisms except bacteria and viruses.

Prokaryote

An organism composed of usually one, but occasionally more, cells that lack defined sub-cellular compartments. All essential material is enclosed within the cell membrane. Includes all bacteria and close relatives.

Actin Filaments

Approximately 5-9 nanometers in diameter. Provide structural support to the plasma membrane. As a cytoskeletal protein provides for movement of organelles within cells.

Why is it called "rough" endoplasmic reticulum?

Because it is coated with small ribosomal particles that for a bumpy coat on cytosolic side of the ER membrane. It is contrasted with smooth ER which lacks these ribosomes

Cytosol vs cytoskeleton

Cytosol is the liquid that fills the interior of a cell. The cytoskeleton is composed of protein filaments found in the cytosol

What is the name of the structures into which DNA is packaged inside the cell nucleus?

DNA is packaged into chromosomes with proteins in the cell nucleus

Rough endoplasmic reticulum

Endoplasmic reticulum that is coated with ribosomes and involved in protein synthesis.

Intermediate Filament

One of three protein components of cytoskeleton. A fibrous protein filament approximately 10 nanometers in diameter. Forms the nucleus lamina that helps protect the cell nucleus.

Why does the mitochondria have two distinct compartments?

Mitochondrial membranes have two layers-an inner and outer membrane. As a result, there are two distinct spaces in the organelle. One between the inner and outer membranes, called the intermembrane space and one within the inner membrane called the matrix space.

Endocytosis

Molecules from outside a cell can be taken inside cell

Exocytosis

Molecules within a cell are secreted into an endosome, a membrane that delivers the molecule to the lysosome

How are proteins segregated in the Golgi apparatus for secretion?

Most proteins contain a signal sequence at its end that tell the Golgi to where in the cell it should be secreted.

Smooth Endoplasmic reticulum

Naked endoplasmic reticulum that lacks ribosomes and are more involved in lipid synthesis.

Microtubule

One of three protein components of the cytoskeleton. Long, cylindrical structures approximately 25 nanometers in diameter. Extend from the centrosome to all parts of the cell, forming tracks on which organelles can travel within the cell. Microtubules can be either kinetocore microtubules or non-kinetocore microtubules. Kinetocore microtubules bind to sister chromatids during mitosis; non-kinetocore microtubules do not

What is the chemical process that occurs in the peroxisomes?

Oxidation. The peroxisomes contain enzymes that oxidize intracellular molecules like fatty acids.

Into which face of the Golgi apparatus do proteins from the ER enter? which face do they exit from?

Proteins enter the Golgi apparatus through the cis face and exit through the trans face.

The cytosol makes up most of what intracellular component?

The cytoplasm

What are the main functions of the cytosol and cytoskeleton?

The cytosol is the site of protein synthesis and the cytoskeleton helps provide intracellular structure and helps with organelle movement in cells.

In what way is the function of the cytoskeleton similar to the function of the lipid bilayer?

The lipid bilayer provides the structure of the cell membrane. The cytoskeleton helps provide the structure of the interior of the cell.

What is the function of the lysosome?

The lysosome functions to remove intracellular debris by digesting it with the acidic enzymes found inside it.

Cytosol

The main component of the cytoplasm that fills the main compartment of Eukaryotic cells.

Intermembrane space

The space between the outer and inner membrane in a mitochondria

Matrix

The space inside the inner membrane of mitochondria

Name the three proteins that compose the cytoskeleton. Which of these are responsible for forming the nuclear lamina?

The three types of protein filaments are actin molecules, microtubules, and intermediate filaments. Intermediate filaments form the nuclear lamina

Does the nucleus allow molecules to pass across its double membrane?

Yes. The nuclear membrane contains pores that allow only certain molecules to pass across its membrane either in or out the cell.