Biology Unit 3

Chloroplast

(in green plant cells) a plastid that contains chlorophyll and in which photosynthesis takes place.

Properties of ALL Cells

All cells, whether they are prokaryotic or eukaryotic, have some common features. The common features of prokaryotic and eukaryotic cells are: DNA, the genetic material contained in one or more chromosomes and located in a nonmembrane bound nucleoid region in prokaryotes and a membrane-bound nucleus in eukaryotes.

Eukaryotes

An organism whose cells contain a nucleus surrounded by a membrane and whose DNA is bound together by proteins (histones) into chromosomes. The cells of eukaryotes also contain an endoplasmic reticulum and numerous specialized organelles not present in prokaryotes, especially mitochondria, Golgi bodies, and lysosomes.

Golgi Apparatus

The Golgi apparatus gathers simple molecules and combines them to make molecules that are more complex. It then takes those big molecules, packages them in vesicles, and either stores them for later use or sends them out of the cell. It is also the organelle that builds lysosomes (cell digestion machines).

Endosymbiotic Theory

The endosymbiosis theory explains how eukaryotic cells may have evolved from prokaryotic cells. Symbiosis is a close relationship between two different organisms. ... Later, a host cell engulfed a prokaryotic cell capable of photosynthesis. This is where the chloroplast and other plastids originated.

Vesicle

a fluid- or air-filled cavity or sac, in particular.

Chlorophyll

a green pigment, present in all green plants and in cyanobacteria, responsible for the absorption of light to provide energy for photosynthesis. Its molecule contains a magnesium atom held in a porphyrin ring.

Prokaryotes

a microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles. Prokaryotes include the bacteria and cyanobacteria.

Smooth Endoplasmic Reticulum

noun, Cell Biology. 1. a network of tubular membranes within the cytoplasm of the cell, occurring either with a smooth surface (smooth endoplasmic reticulum) or studded with ribosomes (rough endoplasmic reticulum) involved in the transport of materials.

Lysosome

an organelle in the cytoplasm of eukaryotic cells containing degradative enzymes enclosed in a membrane.

Nucleus

the central and most important part of an object, movement, or group, forming the basis for its activity and growth.

Cell Membrane

the semipermeable membrane surrounding the cytoplasm of a cell.

Nuclear Membrane

A nuclear membrane, also known as the nucleolemma or karyotheca, is the lipid bilayer membrane which surrounds the genetic material and nucleolus in eukaryotic cells.

Cellular Respiration

Cellular respiration is a set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products.

Circular DNA

Circular DNA is DNA that forms a closed loop and therefore has no free ends that is a complete closed DNA. Examples include: Plasmids - mobile genetic elements. cccDNA - formed by some viruses inside cell nuclei. Circular bacterial chromosomes.

Selectively Permeable

Definition of Selectively Permeable Membranes. All cells are enclosed with a cell membrane. A selectively permeable cell membrane is one that allows certain molecules or ions to pass through it by means of active or passive transport.

Membrane-Bound Organelles

Eukaryotic cells contain many membrane-bound organelles. An organelle is an organized and specialized structure within a living cell. The organelles include the nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, vacuoles, lysosomes, mitochondria, and, in plants, chloroplasts.

Nuclear Pores

Nuclear pore complexes allow the transport of molecules across the nuclear envelope. This transport includes RNA and ribosomal proteins moving from nucleus to the cytoplasm and proteins (such as DNA polymerase and lamins), carbohydrates, signaling molecules and lipids moving into the nucleus.

Cell Theory

In biology, cell theory is the historic scientific theory, now universally accepted, that living organisms are made up of cells. Cells are the basic unit of structure in all organisms and also the basic unit of reproduction.

Properties of Eukaryotes

Like a prokaryotic cell, a eukaryotic cell has a plasma membrane, cytoplasm, and ribosomes. However, unlike prokaryotic cells, eukaryotic cells have: a membrane-bound nucleus. numerous membrane-bound organelles (including the endoplasmic reticulum, Golgi apparatus, chloroplasts, and mitochondria)

Mitochondria

Mitochondria are known as the powerhouses of the cell. They are organelles that act like a digestive system which takes in nutrients, breaks them down, and creates energy rich molecules for the cell. The biochemical processes of the cell are known as cellular respiration.

Properties of Prokaryotes

Prokaryotes lack an organized nucleus and other membrane-bound organelles. Prokaryotic DNA is found in a central part of the cell called the nucleoid. The cell wall of a prokaryote acts as an extra layer of protection, helps maintain cell shape, and prevents dehydration.

Ribosomes

Ribosomes are the protein builders or the protein synthesizers of the cell. They are like construction guys who connect one amino acid at a time and build long chains. Ribosomes are special because they are found in both prokaryotes and eukaryotes.

Rough Endoplasmic Reticulum

Rough ER is found throughout the cell but the density is higher near the nucleus and the Golgi apparatus. Ribosomes on the rough endoplasmic reticulum are called 'membrane bound' and are responsible for the assembly of many proteins. This process is called translation.

Linear DNA

There is also cytoplasmic DNA free-floating in eukaryotic cells. These are also circular and normally contain short copies of chromosomal DNA sequences. Their function is not well understood. In prokaryotes, some species of spirochaetes and bacteria have been found with linear chromosomes.

Cell Wall

a rigid layer of polysaccharides lying outside the plasma membrane of the cells of plants, fungi, and bacteria. In the algae and higher plants, it consists mainly of cellulose.

Nucleolus

a small dense spherical structure in the nucleus of a cell during interphase.

Vacuole

a space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid.

DNA

deoxyribonucleic acid, a self-replicating material present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information.

Cytoplasm

the material or protoplasm within a living cell, excluding the nucleus.

Photosynthesis

the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a byproduct.