ch 4 cells and organelles

Question 1

four phases involved in the appearance of today’s cells

Answer 1

1 abiotic (nonliving) synthesis of simple organic compounds such as amino acids and nitrogenous bases
2 abiotic polymerization of there monomers into macromolecules such as proteins or nucleic acids
3 emergence of a macromolecule capable of replication and storing genetic info
4 encapsulation of the first living molecule within a simple membrane to form the first primitive cell

Question 2

stanley miller

Answer 2

tested the hypothesis that energy from lighting could have powered production of simple organic compounds from atmospheric gases
- after a week of continuous exposure of gases to electrical discharge, he detected two simple amino acids (alanine and glycine) in the flask

Question 3

RNA world hypothesis

Answer 3

hypothesis that RNA existed before DNA and proteins
bc RNA molecules are single stranded, they have the ability to H-bond to themselves and can form complex secondary structures
- RNA is central to the translation process
- small RNAs (ribozymes) can catalyze a range of important chemical reaction required for life
- many critical components of cells (ATP, acteyl-coA, NADH) are either RNA nucleotides or substances related to them

Question 4

liposomes

Answer 4

hollow membrane-bound vesicle of varying size that forms spontaneously when lipids are mixed with water
- may have been the first primitive protocell

Question 5

prokaryote

Answer 5

category of organisms characterized by the absence of a true nucleus and other membrane-bound organelles
- includes bacteria and archaea

Question 6

eukaryotes

Answer 6

category of organisms whose cells are characterized by the presence of a membrane-bounded nucleus and other membrane-bounded organelles
- includes plants, animals, fungi, algae, protozoa

Question 7

bacteria

Answer 7

include most of the commonly encountered single-celled organisms with no nucleus that have traditionally been called bacteria

Question 8

archaea

Answer 8

thrive under harsh conditions that would be fatal to most other organisms
- closer to eukaryotes than bacteria

Question 9

3 main limitations on cell size

Answer 9

1 the need for adequate surface area relative to volume
2 the rates at which molecules can diffuse
3 the need to maintain adequate local concentrations of substances required for necessary cellular functions

Question 10

surface area/volume ratio

Answer 10

major limit on cell size
surface area enables exchanges btw the cell and its surroundings
cell’s volume determines the amount of exchange that must take place, across the available surface area
- at a certain point a large cell will not have a large enough surface area for sufficient uptake of nutrients and releases of wastes

Question 11

cytoplasm

Answer 11

portion of the interior of a eukaryotic cell that is not occupied by the nucleus
- contains organelles, cytosol

Question 12

cytosol

Answer 12

the semifluid substance in which the organelles of the cytoplasm are suspended

Question 13

cytoplasmic streaming

Answer 13

process that involves active movement and mixing of cytoplasmic contents rather than diffusion

Question 14

nucleolus

Answer 14

site of ribosomal RNA synthesis and ribosome assembly

Question 15

nucleoid

Answer 15

where genetic info is stored
attached to the cell membrane

Question 16

cytoskeleton

Answer 16

fundamental structure used for cellular contraction, motility and support
includes the microtubules, microfilaments, and intermediate filaments
also provides scaffolding for transport of vesicles within the cell

Question 17

3 things that different from plant cells and animal cells

Answer 17

plant cells have:
cell wall, vacuole, chloroplasts

Question 18

chromosome

Answer 18

in eukaryotes, a single DNA molecules, complexed with histones and other proteins, that becomes condensed into a compact structure at the time of mitosis or meiosis
- bacterial DNA is circular
- eukaryotic DNA is linear

Question 19

binary fission

Answer 19

method of genetic info replication in bacterial and archaeal cells
- one replicated DNA molecule and half of the cytoplasm going to each daughter cell

Question 20

mitosis/meiosis

Answer 20

method of genetic info replication in eukaryotic cells
- replicate DNA and then distribute their chromosomes into daughter cells by mitosis or meiosis followed by cytokinesis, division of the cytoplasm

Question 21

plasma membrane

Answer 21

bilayer of lipids and proteins that defines the boundary of the cell and regulates the flow of materials into and out of the cell

Question 22

five functions of membranes

Answer 22

1 define the boundaries of a cell and organelles and act as a permeability barrier
2 serve as sites for biological functions such as electron transport
3 possess transport proteins that regulate the movement of substances into and out of cells and organelles
4 contain protein molecules that act as receptors to detect external signals
5 provide mechanisms for cell-to-cell contact, adhesion, and communication

Question 23

roles of proteins in the plasma membrane

Answer 23

• enzymes catalyze reactions associated with the membranes
• anchors for structural components of the cytoskeleton
• transport proteins move substances across the membrane
• receptors for external signals trigger processes within the cell

Question 24

mitochondria

Answer 24

site of aerobic respiration
- energy production
- assists with the degradation of sugars
- contain mtDNA (circular DNA) - maternal inheritance, RNA and proteins
- cristae - infolding of the inner membrane into the matrix, inc total sa, contains the enzymes of electron transport and oxidative phosphorylation

Question 25

chloroplasts

Answer 25

harvests solar energy and converts it to chemical energy - thylakoid - flattened membrane sac suspended in the stroma, in stacks called grana, contains the pigments, enzymes, and electron carriers involved in the light-requiring reactions of photosynthesis - contain their own ribosomes, a circular DNA molecules, and some RNA and protein

Question 26

plastids

Answer 26

any of several types of plant cytoplasmic organelles derived from proplastids - chloroplasts - energy - chromoplasts - coloration in flower, fruits, and other plant structures - amyloplasts - storing starch

Question 27

endosymbiont theory

Answer 27

gene expression process occurring in organelles is similar to the processes occurring in prokaryotes, implying that chloroplasts and mitochondria are the relics of once, free-living bacteria that came to reside in an ancestral prokaryotic cell - came from the discovery that some organelles had their own genomes - absence of oxygen in the early atmosphere limits cells to anaerobic processes

Question 28

promiscuous DNA

Answer 28

DNA that is relocated from one organelle to another

Question 29

endoplasmic reticulum

Answer 29

network of interconnected membranes distributed throughout the cytoplasm and involved in the synthesis, processing, and transport of proteins in eukaryotic cells - cisternae - membrane-bounded flatted sac - lumen - internal space

Question 30

rough ER

Answer 30

studded with ribosomes on the cytoplasmic side of the membrane these ribosomes synthesize polypeptides that accumulate within the membrane or are transported across it to the lumen

Question 31

4 main functions of the rough ER

Answer 31

1 the initial steps of addition of carbs to glycoproteins 2 the folding of polypeptides 3 recognition and removal of misfolded proteins 4 assembly of multimeric protein complexes

Question 32

4 main functions of smooth ER

Answer 32

1 synthesis of lipids and steroids 2 drug detoxification 3 carb metabolism 4 calcium storage

Question 33

golgi apparatus

Answer 33

stacks of flattened, disk-shaped cisternae in eukaryotic cells that are important in the processing and packaging of secretory proteins and in the synthesis of complex polysaccharides (lipids)

Question 34

secretory vesicles

Answer 34

membrane-bounded compartment of a eukaryotic cell that carries secretory proteins from the golgi apparatus to the plasma membrane for exocytosis and that may serve as a storage compartment for such proteins before they are released

Question 35

endomembrane system

Answer 35

responsible for trafficking substances through the cell includes the ER, golgi, secretory vesicles and lysosomes

Question 36

lysosome

Answer 36

membrane-bound organelle containing digestive enzymes capable of degrading all the major classes of biological macromolecules

Question 37

peroxisomes

Answer 37

single-membrane bounded organelle that contains catalase and one or more hydrogen peroxide-generating oxidases and is therefore involved in the metabolism of hydrogen peroxide - prominent in the liver and kidney cells of animals

Question 38

glyoxysomes

Answer 38

specialized type of plant peroxisome that contains some of the enzymes responsible for the conversion of stored fat to carb in germinating seeds

Question 39

leaf peroxisomes

Answer 39

special type of peroxisome found in the leaves of photosynthetic plant cells that contains some of the enzymes involved in photorespiration

Question 40

vacuole

Answer 40

membrane-bound organelle in the cytoplasm of a cell, used for temporary storage of transport

Question 41

central vaculoe

Answer 41

large membrane-bounded organelle present in many plant cells; helps maintain turgor pressure of the plant cell, plays a limited storage role, and is also capable of a lysosome-like function in intracellular digestion

Question 42

ribosomes

Answer 42

site of protein synthesis each cell type has its own unique type of ribosomal RNA

Question 43

sedimentation coefficient

Answer 43

a measure of the rate at which a particle or macromolecule moves in a centrifugal force field expressed in svedberg units (S) 80S - eukaryotes 70S - bacteria and archaea

Question 44

ribosome subunits

Answer 44

large and small subunits eukaryotes - 60S and 40S bacteria and archaea - 50S and 30S

Question 45

cytoskeleton

Answer 45

3D, interconnected network of microtubules, microfilaments, and intermediate filaments that provides structure to the cytoplasm of a eukaryotic cell and plays an important role in cell movement

Question 46

extracellular matrix (ECM)

Answer 46

material secreted by animal cells that fills the spaces btw neighboring cells; consists of a mixture of structural proteins and adhesive glycoproteins embedded in a matrix composed of protein-polysaccharide complexes called proteoglycans

Question 47

processes regulated by the ECM

Answer 47

cell motility and migration cell division cell recognition and adhesion cell differentiation during embryonic development

Question 48

plasmodesma

Answer 48

cytoplasmic channel through pores in the cell walls of two adjacent plant cells, allowing fusion of the plasma membranes and chemical communication btw the cells

Question 49

viruses

Answer 49

subcellular parasite composed of a protein coat and DNA or RNA, incapable on independent existence - invades and infects cells and redirects the host cell's synthetic machinery toward the production of more virus particles

Question 50

fundamental properties of living things

Answer 50

metabolism irritability - perception of and response to external stimuli ability to reproduce - viruses do not satisfy

Question 51

viroid

Answer 51

small, circular RNA molecules that can infect and replicate in host cells even though it does not code for any protein

Question 52

prions

Answer 52

infections, protein-containing particle responsible for neurological diseases - abnormally folded versions of normal cellular proteins - cannot be destroyed by cooking or boiling