Ch. 4 Biology

Cilia + Flagella

Cilia and Flagella - hairlike structures that extend from the cell surface and aid in movement. Cilia are shorter and occur in large numbers, whereas flagella are longer and less numerous. Both cilia and flagella have an outer membrane and an internal structure composed of nine pairs of microtubules around two central microtubules (9+2 arrangement).

Central vacuole

a large, fluid-filled organelle that stores water, enzymes, metabolic wastes and other materials. Can expand and shrink based on the presence of water, can make up as much as 90% of the cells volume

Nucleus

a membrane-bound structure that contains a cell's DNA. The nucleus is a prominent structure within a cell; a protein skeleton called the nuclear matrix maintains the shape of the nucleus

Rough Endoplasmic Reticulum

a system of interconnected flattened sacs with ribosomes embedded within them. Produces phospholipids and proteins. Certain proteins are made by the ribosomes embedded within the rough ER, which accumulate and are then transported by vesicles

Endoplasmic Reticulum (smooth and rough)

a system of membranous tubes and sacs called cisternae. Functions as an intracellular highway. Can be either rough or smooth, although the two types are thought to be continuous. Typically rough ER is much more abundant within cells than smooth ER

Plasma Membrane

also called the cell membrane, is the outer boundary that covers the cell surface and acts as a barrier. All materials must enter or exit through this membrane

Golgi apparatus

another system of flattened, membranous sacs that receive vesicles from the ER and modify the contents of those vesicles as they pass between the stacks of the Golgi. During this modification carbohydrates can be added to proteins or the lipids altered in a way that directs them to their intended destination within the cell

Eukaryote Cell

cells that have both a nucleus and membrane-bound organelles

Prokaryote Cell

cells that lack a membrane-bound nucleus and membrane-bound organelles. Their genetic information is concentrated in an area of the cell known as the nucleoid

Cytoplasm

he area inside a cell that includes all the organelles, the fluid and the cytoskeleton. The cytosol is composed of molecules and small particles in the cytoplasm excluding membrane-bound organelles

Vesicles: Glyoxysomes

in the seeds of some plants, function to break down stored fats to provide energy for developing plant embryos

Smooth Endoplasmic Reticulum

lack ribosomes giving it a smooth appearance, builds lipids, steroid hormones (in ovaries/testes), releases calcium (in the heart). Also present in liver and kidney cells where it helps detoxify drugs and poisons

Plastids

organelles that are similar to mitochondria

Chromoplasts

plastids that contain colorful pigments that may or may not take part in photosynthesis

Cell wall

rigid layer composed of a matrix of proteins and carbohydrates, including cellulose, that lies outside the plasma membrane and serves to provide additional support. Contains pores that allow water, ions and some molecules to enter and exit the cell. Some plants have both a primary and secondary cell wall

Mitochondria

small organelles that transfer energy from organic molecules to ATP. Has an inner and outer phospholipid membrane, the latter of which separates the mitochondrion from the cytosol. The inner membrane has many folds known as cristae that contain proteins to help with the energy transfer. Mitochondria are unique in the fact that they have their own DNA and can reproduce only by the division of pre-existing mitochondria

Ribosomes

small, spherical organelles that build protein. Ribosomes are composed of protein and RNA, and are initially assembled in the nucleus and completed in the cytoplasm. They consist of a large and small subunit, and are either free to move about the cytosol or attached to the rough endoplasmic reticulum

Vesicles

small, spherical, single membrane sacs that accomplish various tasks within the cell. There are several different types

Centrioles

two short cylinders of microtubules that sit at a right angle to each other in the cytoplasm near the nucleus. Only present in animal cells, where they are responsible for microtubule organization during cell division. Basal bodies have the same structure as centrioles but they lie at the base of cilia and flagella to help organize development

Chloroplast

use light energy to make carbohydrates from CO2 and H2O. Contain a system of flattened, membranous sacs called thylakoids. Thylakoids contain the green pigment chlorophyll, which absorbs light and captures energy for the cell

Vesicles: Lysosomes

vesicles that bud from the Golgi and contain digestive enzymes that are used to break down large molecules, including old organelles (autophagy). They are also responsible for breaking down cells when they are old or damaged (autolysis)

Vesicles: Peroxisomes

vesicles that contain enzymes not produced by the Golgi. Typically abundant in liver and kidney cells where they function to neutralize free radicals and detoxify alcohol and other drugs. They can also break down fatty acids, which the mitochondria can then use as an energy source. They get their name from the fact that as a byproduct of their functions hydrogen peroxide is produced

Vesicles: Contractile vacuoles

vesicles that contract in order to dispose of excess water within the cell

Vesicles: Food vacuoles

vesicles that store nutrients

Vesicles: Endosomes

when cells engulf material by surrounding it with cell membrane and budding off resulting in vesicle formation