PH1123 - Inside the cell

Question 1

what are the simplest and oldest prokaryotes?

Answer 1

• bacteria

Question 2

what is DNA in prokaryotes called?

Answer 2

• plasmids

Question 3

what are the function of plasmids? (4)

Answer 3

• fertility; transfer of genetic material between bacteria
• resistance; antibiotics
• degradative; digestion of organic substances
• virulence; turn the bacteria into a pathogen

Question 4

what is the cytoplasm? (3)

Answer 4

• area contained by the plasma membrane
• contains many membrane-bound compartments to facilitate distinct environment within organelles
• defined as everything excluding the nucleus

Question 5

what is the cell cytosol? (3)

Answer 5

• largest compartment of the cell
• composed of densely packed molecules and aqueous gel
• site of many essential chemical reactions
  we can infer that while cytosol is the fluid contained in the cell cytoplasm

Question 6

what chemical reactions occur in the cytosol? (4)

Answer 6

• early steps in nutrient breakdown
• ATP generation (glycolysis)
• manufacture of protein
• signalling transduction

Question 7

what is the mitochondria? (3)

Answer 7

• present in all eukaryotic cells
• function is cellular respiration (in cytosol; anaerobic glycolysis and in mitochondrion; pyruvate oxidation)
• distinctive structure

Question 8

what is the relationship between the number of mitochondria and exercise?

Answer 8

• the more exercise the more mitochondria in muscle cells as cells adapt to a higher energy requirement

Question 9

what are the four separate components of the mitochondria? (4)

Answer 9

• outer membrane
• intermembrane space
• inner membrane
• matrix

Question 10

what are the functions of the outer membrane? (2)

Answer 10

• separation of internal and external environments

- role in cell death (disruption of outer membrane allows proteins from intermembrane space to leak into cytosol)

Question 11

what is in intermembrane space?

Answer 11

• cytochrome c

Question 12

what is cytochrome c important for? (2)

Answer 12

• essential component of the electron transport chain

- important in apoptosis

Question 13

what does the inner membrane of mitochondria contain? (2)

Answer 13

• highly folded to form cristae

- mitochondria of cells with high ATP demand contain more cristae

Question 14

• what does cristae enhance? (2)

Answer 14

• increase surface area of inner membrane

- enhance ability to produce ATP

Question 15

what does the matrix of the mitochondria contain? (2)

Answer 15

• contains most of mitochondrial proteins/enzymes

- mitochondrial ribosomes, tRNA and mtDNA and several copies of the mitochondrial genome

Question 16

what are the principal sites of intracellular digestion?

Answer 16

• lysosomes

Question 17

where are lysosome produced?

Answer 17

• golgi

Question 18

what do lysosomes contain and examples? (5)

Answer 18

• many hydrolytic enzymes
• lipases
• carbohydrates
• nucleases
• proteases

Question 19

what are endosomes? (2)

Answer 19

• eukaryotic cells constantly taking up fluid and molecules via endocytosis
• membrane-bound organelles

Question 20

how are endocytic vesicles formed? (3)

Answer 20

• plasma membrane buds inwards
• pinches off to form intracellular endycotic vesicle
• can fuse with lysosomes or be recycled to the surface

Question 21

what are the functions of endosomes? (3)

Answer 21

• internalisation of nutrients
• regulation of cell surface protein expression
• uptake and digestion of extracellular debris

Question 22

why do cells require endocytosis? (2)

Answer 22

• most molecules required for cellular function are large, polar molecules
• they cannot pass through the hydrophobic portion of the plasma cell membrane by passive means

Question 23

what are the types of endocytosis? (3)

Answer 23

• pinocytosis
• receptor mediated endocytosis (clathrin/caveolin-mediated endocytosis)
• phagocytosis

Question 24

what is pinocytosis? (4)

Answer 24

what is pinocytosis? (4)

• small particles are taken in by a cell by splitting off small vesicles from the cell surface
• nonspecific transport of substances
• cell takes in surrounding fluids
• active transport

Question 25

what is receptor-mediated endocytosis? (3)

Answer 25

• receptor binds to ligand
• captured by clathrin coated pit
• mature pit bud off forming a coated vesicle

Question 26

what is phagcytosis? (3)

Answer 26

• a cell engulfs a solid particle to form an internal compartment known as a phagosome
• pseudopodium
• eliminate debris or pathogens via lysosome

Question 27

what do the professional phagocytes include? (6)

Answer 27

• white blood cells
• macrophages
• monocytes
• neutrophils
• mast cells
• dendritic cells

Question 28

what is the sarcoplasmic reticulum?

Answer 28

• the endoplasmic reticulum in striated muscle cells in the heart and skeletal muscle

Question 29

what are the two functional compartments of the endoplasmic reticulum? (2)

Answer 29

• rough endoplasmic reticulum

- smooth endoplasmic reticulum

Question 30

what is the difference between the rough and smooth endoplasmic reticulum?

Answer 30

• the rough endoplasmic reticulum has ribosomes on its surface

Question 31

what are ribosomes? (2)

Answer 31

• site of protein synthesis (translation)

- link amino acids together in the order specified by messenger RNA (mRNA) molecules

Question 32

what are the two major components of ribosomes? (2)

Answer 32

• the small ribosomal unit

- the large ribosomal subunits

Question 33

what is the function of the endoplasmic reticulum? (5)

Answer 33

• protein manufacture
• protein targeting
• steroid production
• drug detoxification
• Ca2+ storage/ release

Question 34

what is the function of the smooth endoplasmic reticulum?

Answer 34

• lacks ribosomes and is involved in lipid manufacture

Question 35

how does the amount of protein relate to the rough endoplasmic reticulum?

Answer 35

• cells that secrete large amounts of proteins have large amounts of rough endoplasmic reticulum

Question 36

what is glycosylation and what is the purpose? (2)

Answer 36

• carbohydrates attached to proteins

- purpose is folding and stability

Question 37

what part of the endoplasmic reticulum is steroid production, drug detoxification and Ca2+ storage associated with and what does it do? (2)

Answer 37

• smooth endoplasmic reticulum

- storage of proteins and sites of action of many enzymes

Question 38

what are some examples of proteins and enzymes in the smooth endoplasmic reticulum? (3)

Answer 38

• membrane lipid synthesis
• cytochrome p450 enzymes (present in most tissue but especially liver)
• calsequesterin

Question 39

what is calsequesterin?

Answer 39

• calcium binding protein of the sarcoplasmic reticulum

Question 40

what is the function of the sarcoplasmic reticulum?

Answer 40

• forms extensive network surrounding muscle sacromeres and supplies them with Ca2+

Question 41

what is the structure of the sarcoplasmic reticulum? (2)

Answer 41

• tubular network

- smooth muscle cells are spindle-shaped

Question 42

what is the structure of the golgi apparatus? (4)

Answer 42

• flattened disc-shaped sacs (cisternae)
• located near nucleus
• cis (entry) and trans (exit) face
• proteins travel from the endoplasmic reticulum to golgi and within golgi via transport vesicles

Question 43

what is cis and trans of the golgi apparatus? (2)

Answer 43

• incoming transport vesicles (cis)

- outgoing transport vesicles (trans)

Question 44

what is the function of the golgi apparatus? (3)

Answer 44

• secretory pathway
• lysosome formation
• protein modification and sorting