AP Biology Unit Two Review

what is the nucleus?

contains most of the genes in the eukaryotic cell

what is the nuclear envelope?

encloses the nucleus, separating its contents from the cytoplasm

what is the nuclear lamina?

a netlike array of proteins filaments (in animal cells, called intermediate filaments) that maintains the shape of the nucleus by mechanically supporting the nuclear envelope

what are chromosomes?

within the nucleus, the DNA is organized into these discrete units, or structures that carry the genetic information

what is chromatin?

 the complex of DNA and proteins making up chromosomes is called chromatin, used to diffuse mass in micrographs

what is the nucleolus?

densely strained granules and fibers adjoining part of the chromatin, also inside proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes

what are ribosomes?

complexes made of ribosomal RNA and proteins, carry out protein synthesis (but are not membrane bound, thus not considered organelles)

what is endoplasmic reticulum?

an extensive network of membranes that accounts for more than half the total membrane in many eukaryotic cells

what is the smooth ER?

lacks outer surface ribosomes, function in diverse metabolic processes such as synthesis of lipids, metabolism of carbs, detoxification of drugs and poisons, and storage of calcium ions

what is rough ER?

has outer surface ribosomes, secures proteins produced by ribosomes attached (ex: certain pancreatic cells synthesize protein insulin in the ER and secrete this hormone into the bloodstream)

what is the golgi apparatus?

think of it as like a warehouse of receiving, sorting, shipping, and even more manufacturing (proteins are modified and stored and then sent other places)

what are lysosomes?

a membranous sac of hydrolytic enyzemes that many eukaryotic cells use to hydrolyze macromolecules

what are vacuoles?

largest vesicles derived from the endoplasmic reticulum and golgi apparatus, making theme an integral part of a cell’s endomembrane system transporting solutes, the solution inside differs in compo from the cytosol 

what is a food vacuole?

formed in a process called phagocytosis, formed by fusing with a lysosome whose enzymes digest food

what are contractile vacuoles?

they pump excess water out of the cell, thereby maintaining a suitable concentration of ions and molecules inside the cell

what are central vacuoles?

also known as cell sap, the plant cell’s main repository of inorganic ions including potassium and chloride, playing a major role in the growth of plant cells, which enlarge as the vacuole absorbs water, enabling the cell to become larger with a minimal investment in new cytoplasm

what is the endomembrane system?

overall, the endomembrane system shows the flow of membrane lipids and proteins that move from the E to the golgi and then elsewhere, its molecular composition and metabolic functions are modified, along with those of its contents, being a complex and dynamic player in the cell’s compartmental organization

what is the mitochondria?

the site of cellular respiration, which is the metabolic process that uses oxygen to drive the generation of ATP by extracting energy from sugars, fats, and other fuels

what is the mitochondrial matrix?

enclosed by the inner membrane, containing many different enzymes as well as the mitochondrial DNA and ribosomes

what is cristae?

an infolding of the inner membrane of a mitochondria, giving the inner mitochondrial membrane a large surface area, thus enhancing the productivity of cellular respiration

what are plastids?

a family of plant organelles

what is amyloplast?

a colorless organelle that stores starch, particularly in roots and tubers 

what are chromoplast?

organelles that have pigments that give fruits and flowers their orange and yellow hues 

what is a chlorplast?

the site of photosynthesis inside a plant cell

what are thylakoids?

membranous system in the form of flattened, interconnected sacs called thylakoids, stacked like poker chips, and each stack is called a granum, which abide inside of chloroplast

what are stroma?

the fluid outside the thylakoids, containing the chloroplast DNA and ribosomes, as well as many enzymes

what are peroxisomes?

a specialized metabolic compartment bounded by a single membrane, they contain enzymes that remove hydrogen atoms from certain molecules and transfer them to oxygen, producing hydrogen peroxide

what is the cytoskeleton?

a network of rivers extending throughout the cytoplasm, playing a major role in organizing the structures and activities of the cell

what are microtubules?

thickest type of fibers

what are centrosomes and centrioles?

centrosomes, are regions that are often located near the nucleus and are considered a “microtubule-organizing center”, within each centrosome there is a pair of centrioles, each composed of nine sets of triplet microtubules arranged in a ring (these are in animal cells, many other eukaryotic cells lack them and organize microtubules by other means)

what are cilia and flagella (including basal body)?

in eukaryotes, a specialized arrangement of microtubules is responsible for the beating of flagella and cilia, microtubule-containing extensions that project from some cells, many protists are propelled through water by cilia or flagella that act as locomotor appendages, and the sperm of animals, algae, and some plants have flagella, when they extend from cells that are held in place as part of a tissue layer, they can move fluid over the surface of the tissue, the microtubule assembly of a cilium or flagellum is anchored in the cell of a basal body, which is structurally similar to a centriole

what is dynein walking?

dynein are large motor proteins that are attached along each outer microtubule doublet, a typical dynein protein has two “feet” that “walk” along the microtubules of the adjacent doublet, using ATP for energy, one foot maintains contact, while the other releases and reattaches one step one step farther along the microtubule

what are microfilaments?

thin, solid rods, also called actin filaments  because they are built from molecules of actin, a globular protein

what is actin?

a globular protein building microfilaments

what is myosin?

these are thousands of actin filaments and thicker filaments of a motor protein, called myosin interact to cause contraction of muscles cells, involved in the amoeboid (crawling) movement of the cells

what is pseudopodia?

when macrophage crawls along a surface and reaches out to the bacteria with thin cell extensions, which are called pseudopodia (specifically filopodia)

what is cytoplasmic streaming?

cytoplasmic streaming is when the fluid cytoplasm and the organelles inside flow continuously

what are intermediate filaments?

fibrous protein polymers that form part of the cell’s cytoskeleton

what are cell walls?

protective layers found outside the plasma in the cells of plants, fungi, prokaryotes, and some protist, providing structural support and used to compose cellulose and chitin

what is the primary cell wall?

the first cell wall, and is relatively thin and flexible, located outside the plasma membrane and is part of the multilayered partition between plant cells that are next to each other 

what is the middle lamella?

very thin layer between primary cell walls and the other cells around it, basically gluing plant cells together 

what is the secondary cell wall?

a thicker cell wall that develops when a plant cell matures

what is the extracellular matrix?

the main ingredients of the ECM are glycoproteins and other carbohydrate-containing molecules secreted by the cells, surrounding the animal cells (kinda like a cell wall but not) 

what is collagen?

forming strong fibers outside the cells, this glycoprotein accounts for about 40% of the total protein in the human body, these fibers are embedded ina network woven of secreted proteoglycans

what are proteoglycans?

consist of a small core protein with many carbohydrate chains covalently attached, it may be up to 95% carbohydrates

what is fibronectin?

fibronectin and other ECM glycoproteins bind to cell-surface receptor proteins called integrins that are built into the plasma membrane

what are integrins?

spanning the membrane and bind on their cytoplasmic side to associated proteins attached to the microfilaments of the cytoskeleton, (think of the word integrate), integrins are in a position to transmit signals between the ECM and the cytoskeleton and thus to integrate changes occurring outside and inside the cell 

what are intercellular junctions and why are they important?

intercellular junctions are protein structures that connect cells that are next to each other, and they are important because they allow tissues to maintain structures, form barriers, and communicate 

what is plasmodesmata?

the membrane lined channels filled with cytosol, unifying most of a plant into one living continuum 

what are tight junctions?

in animal cells, the plasma membranes of neighboring cells are rightly pressed together, bonding together by specific proteins, forming continuous cells around the cells and establishing a barrier

what are desmosomes?

in animal cells, function like rivets, fastening cells together into strong sheets, intermediate filaments made of sturdy keratin proteins anchor desmosomes in the cytoplasm

what are gap junctions?

in animal cells, provide cytoplasmic channels from one cell to an adjacent cell and in this way are similar to an adjacent cell and in this way are similar to plasmodesmata in plants, create pores through which ions, sugars, amino acids, and other small molecules may pass, necessary for communication between cells in many types of tissues