Chapter 2 Flashcards

Question

In eukaryotes, each DNA molecule is linear, and associates with proteins into chromosomes?

Answer 1

Ribosomal subunits are formed in nucleoli and exit the nucleus through nuclear pore complexes. In the cytoplasm, they combine with other rRNA molecules and proteins to form ribosomes

Answer 2

Ribosomes are the site of translation, where mRNA is converted into proteins. Expression of genes is carefully controlled, according with the function of each cell

Answer 3

Spherical, rodlike, spiral

Answer 4

Endomembrane collection of interrelated internal membranous sacs that divide a cell into functional and structural compartments

Answer 5

The membranes may be connected directly (physically) or indirectly by vesicles, small membrane-bound sacs that transfer substances between parts of the system ER Nuclear envelope Golgi Lysosomes Vacuoles Plasma membrane

Answer 6

Endoplasmic reticulum (ER) → Extensive interconnected network (reticulum) of membranous channels and cisternae → Each cisterna is formed by a single membrane that surrounds an enclosed space (ER lumen) ER occurs in two forms: rough ER and smooth ER

Answer 7

Rough ER has many ribosomes attached to its outer surface Proteins that are made on ribosomes attached to the ER enter the ER lumen or become integrated into the ER membrane Rough ER contains ribosomes, proteins, lumen, carbohydrates Proteins are then delivered to other regions of the cell (Golgi complex) using small vesicles that form from the ER Smooth ER membranes have no ribosomes attached to their surfaces (no porteins being made) synthesizes lipids that become part of cell membranes, stores Ca2+ ions and cell signaling In the liver, smooth ER converts drugs, poisons, and toxic by-products into substances that can be tolerated or more easily and removed from the bod

Answer 8

The Golgi complex consists of a stack of flattened, membranous sacs (cisternae) Responsible for final modification, sorting, + distribution of proteins + lipids Proteins enter cis face through vesicles and modified porteins exit by trans face to plasma membrane (from which they leave out of cell by exocytosis) Add carbs, lipids + functional groups (can cut but NOT add amino acids)

Answer 9

A secretory vesicle fuses with the okasma membrance, releasing the vesicle contets to the cell exterior. The vesicle membrane becomes a part of the plasma mebrane Can be used to deliver plasma membrane proteins to the plasma membrane.

Answer 10

The Golgi complex “sorts” proteins to ensure they are delivered to their final destination. (some proteins are taken back). Proteins to be secreted from the cell are transported to the plasma membrane in secretory vesicles, which release their contents to the exterior by exocytosis The membrane of the vesicle fuses with the plasma membrane and becomes part of the plasma membrane

Answer 11

Materials from the cell exterior are enclosed in a segment of plasma membrane that pockets inward and pinches off as an endocytic vesicle Vesicles also form by the reverse process, endocytosis, which brings molecules into the cell from the exterior The plasma membrane forms a pocket, which bulges inward and pinches off into the cytoplasm as an endocytic vesicle Endocytic vesicles carry materials to the Golgi complex or other destinations such as lysosomes

Answer 12

Lysosomes are small, membrane-bound compartments containing hydrolytic enzymes that digest complex molecules ► Cells recycle the constituents of these molecules Found in animals + plants (eukaryotes) Formed by budding from golgi complex pH in lysosome is acidic (5) < pH of cytosol (7.2) - Lysosomes do not digest endocytic vesicles ● Secretory vesicles carry materials out ● Endocytic vesicles carry materials in In lysosomal storage diseases, one of the hydrolytic enzymes normally found in the lysosome is absent (cannot break down and recycle things).

Answer 13

1. Proteins made by ER ribosomes enter ek membranes or the space inside ER cisternae. Chemical modification of some proteins begins. Membrane lipids are also made in the ER. 2. Vesicles bud from the ER membrane and then transport unfinished proteins and lipids to the Golgi complex. 3. Protein and lipid modification is completed in the Golgi complex, and products are sorted into vesicles that bud from the complex. 4. Secretory vesicles budding from the Golgi membranes transport finished products to the plasma membrane. The products are released by exocytosis. Other vesicles remain in storage in the cytoplasm. 5. Lysosomes budding from the Golgi membranes contain hydrolytic enzymes that digest damaged organelles or the contents of endocytic vesicles that fuse with them. Endocytic vesicles form at the plasma membrane and move into the cytoplasm.

Answer 14

Nucleoid - central region of a prokaryotic cell with no boundary membrane separating it from the cytoplasm (containing cytosol + cytoskeleton), where DNA replication and RNA transcription occur Genetic material of archaea and bacteria in nucleoid

Answer 15

Endomembrane system - a collection of internal membranes that divide cell into structural + functional regions ● Include golgi complex, ER, + nuclear envelope - Internal membranes formed infolding of plasma membrane ● Most often the sites of photosynthetic + respiratory e- transport chains

Answer 16

Plasma membrane surrounded by cell wall - Cell wall - provides rigidity to prokaryotic cells - Cell wall coated w/ glycocalyx - a carbohydrate coat covering the cell surface ● Glycocalyx diffused + loosely associated w/ cells = slime layer ● Glycocalyx gelatinous + more firmly attached to cells = capsule ● Helps prokaryotic cells from physical damage + desiccation ● can enable cell to attach to surfaces s/a other prokaryotic cells (forming a colony), eukaryotic cells (streptococcus attaching to lung cells), or non-living substrate (rock)

Answer 17

DNA found in nucleus - Space inside nucleus mostly occupied by chromatin (combo of DNA + proteins) - DNA molecule is linear and organized as chromosome ● DNA → histones → nucleosome (made of 8 histones) → chromatin (4 nucleosomes) → chromosome

Answer 18

Nucleolus (plural - nucleoli) - nuclear sites of rRNA transcription, processing + ribosome assembly in eukaryotes - Function ● Info in rRNA genes copied into rRNA molecules, combine w/ proteins to form ribosomal subunits ● Ribosomal subunits leave nucleoli + exit nucleus through nuclear pore complexes to enter cytoplasm = join onto mRNA to form complete ribosome - Ribosomal subunits made of one large + one small subunit

Answer 19

In eukaryotes, membrane separating nucleus from cytoplasm

Answer 20

Large vesicles identified as distinct organelles of plant cells Tonoplast (surrounds central vacuole) contains transport proteins moving substances in/out of central vacuole Store salts, organic acids, sugars, storage proteins, waste products, pigments

Answer 21

Outer limit of cytoplasm responsible for regulation of substances moving in/out of cells Bilayer made of lipids w/ embedded protein molecules Nuclear proteins NOT an integral protein in plasma membranes

Answer 22

Mitochondrion (plural - mitochondria) - membrane-bound organelle responsible for synthesis ofmost of ATP in eukaryotic cells (where cellular respiration occurs) ● 2 membranes surrounding mitochondrial matrix (innermost compartment/liquid of mitochondrion) - outer (covers organelle) & inner (expanded by cristae) ● ATP synthesis in matrix + cristae ● Folds = more SA for cellular respiration ● Inner membrane SA > outer membrane SA

Answer 23

Membrane-bound organelles in which cellular respiration occurs Cellular respiration is the process by which energy-rich food molecules are broken down to water and carbon dioxide by mitochondrial reactions, and energy is converted to ATP Require oxygen for cellular respiration → In animals, breathing provides the oxygen to keep the process going Two membranes surrounding the inner soluble compartment (the mitochondrial matrix) The outer mitochondrial membrane covers the organelle; the inner mitochondrial membrane is expanded by folds called cristae

Answer 24

The cristae and matrix

Answer 25

An interconnected system of protein fibers and tubes that extends throughout the cytoplasm The cytoskeleton maintains a cell’s characteristic shape and internal organization, and functions in movement The cytoskeleton of animal cells is comprised of microtubules, intermediate filaments, and microfilaments

Answer 26

Assembled from dimers of alpha (+ end) and beta (- end) tubulin proteins - 25 nm outer diameter (15 nm inner diameter) - DO NOT hold CELLS in place - Provide tracks for vesicles by moving along microtubules through push/pull mvmts (ex. Motor proteins s/a kinesin & diesin), vesicles move between the cell interior and the plasma membrane - Have polarity (+ and - ends) - Dynamic = change lengths by addition/removal of tubulin dimers - Tubulin → microtubules → centrioles (9 triplets of microtub) → centrosome (comprised of two short, barrel-shaped structures- centrioles) → MTOC (microtubule organizing centre - holds organelles in place) - Organizes microtubule arrays that are involved in various processes » mitosis, holding organelles in position, and others

Answer 27

cytoskeletal filament providing mechanical strength + structural support to cells in tissues Intermediate in size between microtubules and microfilaments (8-12 nm) Assembled from a large and varied group of intermediate filament proteins Occur singly, in parallel bundles, and in interlinked networks Provides structural support in many cells and tissues, and are tissue-specific in their protein composition Stable, form + stay the way they established Microfilaments < intermediate filaments < microtubules

Answer 28

thin protein fibres assembled from actin subunits 5-7 nm diameter Polarity (+ and - ends) Involved in cytoplasmic streaming - intracellular movmentt of cytoplasm Can transport nutrients, proteins + organelles in plant/animal cells → responsible for amoeboid movment Structural + locomotor functions (contractile elements in muscle fibres, divide cytoplasm when animal cells divide)

Answer 29

· Several structures are found in plant cells but not in animal cells: ► Chloroplasts ► A large central vacuole ► Plant cell walls Chloroplasts also occur in algal protists, and cell walls in algal protists and fungi

Answer 30

Elongated, motile structures that extend from the cell surface Cilia are shorter than flagella and occur in greater numbers Movements of a flagellum propel a cell through a watery medium, and cilia move fluids over the cell surface Cilia and flagella are found in protozoa and algae Many types of animal cells have flagella—the tail of a sperm cell is a flagellum—as do the reproductive cells of some plants Cilia covers the surface of cells lining cavities or tubs in some parts of the body. (cilia on cells lining the ventricles (cavities) of the brain circulate fluid through the brain, and cilia in the oviducts conduct eggs from the ovaries to the uterus. genes that encode the components of the flagellar apparatus of cells of Bacteria, Archaea, and Eukarya are different in each case.

Answer 31

Flagella beat in smooth, S-shaped waves that travel from base to tip. Cilia beat in an oarlike power stroke (dark orange) followed by a recovery stroke (light orange).

Answer 32

Photoautotroph (produces its own energy using light)

Answer 33

Chloroplasts yellow-green plastids—the sites of photosynthesis in plant cells Others colorless and store starch (or other molecules), others are brightly colored with pigments such as carotenoids or lycopene Contain DNA genomes + molecular machinery for gene expression and synthesis of porteins and ribosomes * Some of the proteins within plastids are encoded by their genomes; but most are encoded by nuclear genes and are imported into the organelles from the cytosol

Answer 34

● Surrounded by inner + outer membrane (inside the inner membrane = stroma) ● Inside stroma = thylakoids (flattened, closed sacs) which contain chlorophyll (green pigment converted into chem energy in photosynthesis) - Thylakoids stacked = grana - Thylakoid membrane encloses thylakoid lumen - soluble compartment * Thylakoid membranes contain chlorophyll, a green pigment that absorbs light energy that is ultimately converted into chemical energy in photosynthesis

Answer 35

Vacuoles - large vesicles identified as distinct organelles of plant cells 90% or more of the cell’s volume may be occupied by one or more large central vacuoles - Tonoplast (surrounds central vacuole) contains transport proteins moving substances in/out of central vacuole - Store salts, organic acids, sugars, storage proteins, waste products, pigments ● Contain enzymes breaking down biological molecules ● Provide chem defences against pathogenic organisms ●Supports the cell structure ●Pigments produce colors of many flowers and fruits (e.g. red-blue anthocyanin pigments used by flowers)

Answer 36

- Plant cell walls ● Support individual cells, support + protect against invading bacteria ● Cell walls made of cellulose (long polymers of glucose - most abundant molecule), Aggregate into bundles called microfibrils, Embedded in a network of other polysaccharides ● Walls of adjacent cells held together by middle lamela (layer of polysaccharides - pectin) ●Contribute to the turgor pressure produced in the central vacuole

Answer 37

cell walls perforated by cytosol-filled channels lined by plasma membrane Primary and secondary cell walls are perforated by plasmodesmata 1000 to 100 000 plasmodesmata in typical plant cell wall Allow ions + small molecules to move directly from one cell to another through connecting cytosol w/o having to penetrate plasma membrane or cell walls Proteins + nucleic acids move through some plasmodesmata using energy dependent processes

Answer 38

Cell adhesion molecules organize animal cells into tissues and organs Animal cells have specialized structures that organize cells at three levels: 1. Individual cell adhesion molecules bind cells together 2. Cell junctions seal the spaces between cells and provide direct communication between cells 3. Extracellular matrix (ECM) supports and protects cells and provides mechanical linkages between tissues

Answer 39

Glycoproteins (proteins with carbohydrates, made in the ER) in the plasma membrane that bind to specific molecules on other cells ● Organize animal cells into tissues and organs Cancer cells typically lose these adhesions, allowing them to break loose and migrate to new locations (which allow cancer cells to move around the body) Cell junctions reinforce cell adhesions and provide avenues of communication

Answer 40

Anchoring, tight and gap

Answer 41

Form buttonlike spots, or belts, that run entirely around cells, “welding” adjacent cells together Desmosomes- anchoring junctions with intermediate filaments that anchor the junction in underlying cytoplasm Adheres- anchoring junctions with microfilaments as the anchoring cytoskeletal component ● Wield adjacent cells together ● Most common in tissues subject to stretching, shear ● Have strings poking out ● Ex. heart muscle, skin

Answer 42

Regions of tight connections between membranes of adjacent cells Seal spaces between cells in cell layers that cover internal organs, outer surface of the body, or layers that line internal cavities and ducts Formed by direct fusion of proteins on the outer surfaces of plasma membranes of adjacent Connection so tight it can keep particles as small as ions from moving b/w cells in layers Look like stitch work ● Ex. tight junctions b/w stomach, intestine, bladder

Answer 43

Open direct channels that allow ions and small molecules to pass directly from one cell to another Hollow protein cylinders embedded in plasma membranes of adjacent cells connects the cytoplasm of one cell with the cytoplasm of the next Gap junctions communicate between cells within a tissue, such as heart muscle tissue Occur b/w cells w/in almost all body tissues but not b/w cells of diff tissues ● Ex. heart muscle tissues, smooth muscle tissues forming uterus

Answer 44

Extracellular Matrix (ECM) - molecular system supporting and protecting cells + providing mechanical linkages Many animal cells are embedded in an ECM that consists of proteins and polysaccharides secreted by the cells themselves ECM provides protection and support, also affects cell division, adhesion, motility, and embryonic development, and takes part in reactions to wounds and disease - Structure + support - Forms mass of skin, bones, tendons, highly specialized extracellular structures - Glycoproteins main component of ECM - Consistency of ECM (from soft/jellylike to hard/elastic) depends on network of proteoglycans that surround collagen fibres ● Tendons = almost pure collagen = tough + elastic * In cartilage, which contains a high proportion of interlinked glycoproteins, the ECM is relatively soft * In bone, the network is impregnated with mineral crystals, producing an ECM that is dense and hard, yet elastic

Answer 45

- False (single-cell organisms exist) - 1 cell in prokaryotes 1 or more cells in eukaryotes

Answer 46

Area-to-volume ratio (volume of cell determines how much chemical reaction, must be proportional)

Answer 47

False (hydrophobic- doesn’t like water)

Answer 48

Phospholipid molecules ( hydrophilic tails and hydrophobic heads)

Answer 49

Head, tail, tail, head

Answer 50

False (a gene codes for a protein)

Answer 51

Cytoplasm ( cytoplasm contains cytosol and cytoskeleton)

Answer 52

Nucleoid (nucleolus in the nucleus)

Answer 53

Glycocalyx, capsule, slime layer (slime is hard it is like a pill which Is capsule)

Answer 54

False (some eukaryotes have cell walls like plants)

Answer 55

Nuclear (recognition so your body knows which cells are cells)

Answer 56

False (prokaryotic cells do not have nucellus and nucleoli, true for eukaryotes)

Answer 57

False (one large unit, one small unit)

Answer 58

True (in the rough ER no smooth ER)

Answer 59

Synthesise lipids (not synthesize proteins because rough ER is where proteins are made because it has ribosomes)

Answer 60

True (rough ER to the Golgi to the vesicles)

Answer 61

False (enter on the cis face)

Answer 62

Add amino acids (ribosomes are on rough ER which add amino acids)

Answer 63

False (secretory vesicles carry out materials, endocytic bring materials in)

Answer 64

Endocytic vesicles (morphs with vesicle)

Answer 65

True (inside mitochondria is called matrix)

Answer 66

Microfilaments

Answer 67

Hold cells in place (providing tracks for vesicles- kinesin and disoin are molecules that move along the microtubes which provide tracks)

Answer 68

Hold cells in place (providing tracks for vesicles- kinesin and disoin are molecules that move along the microtubes which provide tracks)

Answer 69

False (kinesin and disoin not myosin)

Answer 70

provides structural support (Microtubules are 25 cm and provide tracks for vesicles.)

Answer 71

they have polarity( different charges on different ends), they have acting subunits, involved in cytoplasmic streaming (all true), microtubules have polarity

Answer 72

Cytoskeleton (eukaryotic and prokaryotic cells have cytoskeletons)