Structure and Function of Cell Organelles (Module 1.2.1)

Structure and Function of Cell Organelles (Module 1.2.1)

have: 1) a membrane-bound nucleus; 2) numerous membrane-bound organelles such as the endoplasmic reticulum, Golgi apparatus, chloroplasts, mitochondria, and others; and 3) several, rod-shaped chromosomes.

eukaryotic cells

, a phospholipid bilayer with embedded proteins that separates the internal contents of the cell from its surrounding environment. controls the passage of organic molecules, ions, water, and oxygen into and out of the cell. Wastes (such as carbon dioxide and ammonia) also leave the cell by passing through the:

plasma membrane

cytoplasm

is the entire region of a cell between the plasma membrane and the nuclear envelope

the cytoskeleton, and various chemicals

cytosol

houses the cell’s DNA and directs the synthesis of ribosomes and proteins

nucleus

is a double-membrane structure that constitutes the outermost portion of the nucleus. Both the inner and outer membranes of the nuclear envelope are phospholipid bilayers. is punctuated with pores that control the passage of ions, molecules, and RNA between the nucleoplasm and cytoplasm.

nuclear envelope

is the semi-solid fluid inside the nucleus, where we find the chromatin and the nucleolus. Chromatin and Ch

nucleoplasm

These unwound protein-chromosome complexes. describes the material that makes up the chromosomes both when condensed and decondensed.

chromatin

are structures within the nucleus that are made up of DNA, the hereditary material.

Chromosomes

aggregates the ribosomal RNA with associated proteins to assemble the ribosomal subunits that are then transported out through the pores in the nuclear envelope to the cytoplasm.

nucleolus

are the cellular structures responsible for protein synthesis. single, tiny dots that float freely in the cytoplasm.

Ribosomes

are often called the “powerhouses” or “energy factories” of a cell because they are responsible for making adenosine triphosphate (ATP), the cell’s main energy-carrying molecule. . ATP represents the short-term stored energy of the cell.

Mitochondria

are small, round organelles enclosed by single membranes. They carry out oxidation reactions that break down fatty acids and amino acids.

Peroxisomes

are membrane-bound sacs that function in storage and transport

Vesicles and vacuoles

microtubule-organizing center found near the nuclei of animal cells. is a cylinder of nine triplets of microtubules.

centrosome

are the cell’s “garbage disposal.

lysosomes

is a rigid covering that protects the cell, provides structural support, and gives shape to the cell.

cell wall

have their own DNA and ribosomes. are plant cell organelles that carry out photosynthesis

Chloroplasts

is the series of reactions that use carbon dioxide, water, and light energy to make glucose and oxygen. This is a major difference between plants and animals; plants (autotrophs) are able to make their own food, like sugars, while animals (heterotrophs) must ingest their food.

Photosynthesis

space enclosed by a chloroplast’s inner membrane is a set of interconnected and stacked fluid-filled membrane sacs.

thylakoids

The fluid enclosed by the inner membrane that surrounds the grana.

stroma

plays a key role in regulating the cell’s concentration of water in changing environmental conditions.

central vacuole

describes the structure of the plasma membrane as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character. explanation proposed by Singer and Nicolson.

fluid mosaic model.

are found on the exterior and interior surfaces of membranes, attached either to integral proteins or to phospholipids. “cell-specific” proteins.

Peripheral proteins

they allow some substances to pass through, but not others.

selectively permeable

is a naturally occurring phenomenon and does not require the cell to exert any of its energy to accomplish the movement. substances move from an area of higher concentration to an area of lower concentration.

Passive transport

is a passive process of transport. A single substance tends to move from an area of high concentration to an area of low concentration until the concentration is equal across a space

Diffusion

also called facilitated diffusion, materials diffuse across the plasma membrane with the help of membrane proteins. A concentration gradient exists that would allow these materials to diffuse into the cell without expending cellular energy.

facilitated transport

is the movement of water through a semipermeable membrane according to the concentration gradient of water across the membrane, which is inversely proportional to the concentration of solutes. transports only water across a membrane and the membrane limits the diffusion of solutes in the water. Is is a special case of diffusion

Osmosis

describes how an extracellular solution can change the volume of a cell by affecting osmosis

Tonicity

describes the total solute concentration of the solution.

Osmolarity

the extracellular fluid has lower osmolarity than the fluid inside the cell, and water enters the cell.

hypotonic

refers to the extracellular fluid having a higher osmolarity than the cell’s cytoplasm; therefore, the fluid contains less water than the cell does. Because the cell has a relatively higher concentration of water, water will leave the cell.

hypertonic

the extracellular fluid has the same osmolarity as the cell. If the osmolarity of the cell matches that of the extracellular fluid, there will be no net movement of water into or out of the cell, although water will still move in and out.

isotonic

cell membrane detaches from the wall and constricts the cytoplasm.

plasmolysis

mechanisms require the use of the cell’s energy, usually in the form of adenosine triphosphate (ATP)

Active transport

is a type of active transport that moves particles, such as large molecules, parts of cells, and even whole cells, into a cell.

Endocytosis

This literally means “cell drinking” and was named at a time when the assumption was that the cell was purposefully taking in extracellular fluid.

pinocytosis

is to expel material from the cell into the extracellular fluid

Exocytosis

Only the predominantly single-celled organisms of the domains Bacteria and Archaea are classified as

prokaryotes

Cells of animals, plants, fungi, and protists are all

eukaryotes