CH 3: Cell Level Flashcards
1
Q
cell - parts
A
- plasma membrane
- separates cell’s internal environment from outside environment
- selective barrier - cytoplasm - made of:
- cytosol: fluid and solutes
- organelles: subcellular structures - nucleus
- contains nucleolus and DNA
2
Q
plasma membrane
A
- separates cell’s internal environment from outside environment
- flexible but sturdy barrier that surrounds and contains cytoplasm of cell
- responsible for bidirectional transport of molecules (oxygen, nutrients and wastes)
- selective permeable to some molecules
- many cell reactions take place there as many enzymes are embedded in the membrane
3
Q
cytoplasm
A
made of:
- cytosol: fluid and solutes
- organelles: subcellular structures
4
Q
nucleus
A
contains:
- nucleolus
- DNA
5
Q
cell membrane - fluid part of fluid mosaic
A
- fluid mosaic of lipids and proteins
- phospholipid molecules form flexible layer
- protein molecules embedded in plasma membrane
- carbohydrates act as cell identification tags on surface of plasma membrane
6
Q
cell membrane - mosaic portion of fluid mosaic
A
- phospholipid bilayer
- amphipatic: polar heads associate with water and non-polar tails cluster together away from water
7
Q
cholesterol
A
- embedded in both layers of the membrane
- attached to phospholipid tails
- regulates membrane fluidity:
- warm temperatures: restrains movement of phospholipids and constrains fluidity
- cool temperatures: prevents phospholipids from tightly packing and promotes fluidity
8
Q
cholesterol regulating membrane fluidity
A
- warm temperatures: restrains movement of phospholipids and constrains fluidity
- cool temperatures: prevents phospholipids from tightly packing and promotes fluidity
9
Q
transmembrane proteins
A
subtype of integral proteins that span across membrane
10
Q
plasma membrane proteins - function
A
- form channels
- receptor proteins
- enzymes
- linkers
- cell identity markers
11
Q
channel proteins
A
transmembrane protein: passageway allowing specific substances to pass through membrane (ex. ion channel)
12
Q
receptor proteins
A
transmembrane protein: bind to substance outside of cell and transmit signal inside the cell (ex. hormone receptor)
13
Q
enzymes
A
speed up chemical reactions
14
Q
linkers
A
- give cell shape and structure by interacting with the cytoskeleton
- join cells together to form tissues
15
Q
cell identity markers
A
- include glycoproteins and glycolipids
- allow cells to recognize other similar cells
16
Q
carbohydrates
A
found on glycocalix (extensive sugary coat on the outer surface of the cell)
- attach to proteins = glycoproteins
- attach to lipids = glycolipids
17
Q
glycocalix
A
- glyco = sugar, calix = cup-like structure
- extensive sugary coat on the outer surface of the cell
- function: cell recognition and cell signaling
18
Q
membrane permeability
A
- selectively permeable
- permeable to small, nonpolar, uncharged molecules
- impermeable to ions, charged and polar molecules
- transmembrane proteins act as channels or transporters for molecules that cannot cross lipid bilayer
- too big molecules require vesicular transport: endocytosis, exocytosis and transcytosis
19
Q
vesicular transport
A
- endocytosis
- exocytosis
- transcytosis
20
Q
passive transport
A
- does not requrie en-
- solutes move down their concentration gradient from high to low
- may or may not require a membrane protein
- includes: simple diffusion and facilitated diffusion
21
Q
active transport
A
- requires en-
- solutes pumped against their concentration gradient from low tow high
- requires membrane protein
- includes: primary active transport and secondary active transport
22
Q
diffusion
A
- movement of solutes from area of high solute concentration to an area of low solute concentration
- substances move down their concentration gradient independently of other substances
- occurs even after equilibrium has been reached due to kinetic en- of molecules
23
Q
factors affecting diffusion
A
- steepness of concentration gradient
- temperature
- size or mass of diffusing substance
- SA
- diffusion distance
24
Q
passive transport - types
A
- simple diffusion
- facilitated diffusion
25
simple diffusion
type of passive transport
| - small, uncherged, non-polar molecules (O2, CO2, ...) cross the membrane down their concentration gradient
26
facilitated diffusion
type of passive transport
- some molecules cross the membrane via selective protein pores
- no energy required: substance moving from higher concentration to lower concentration
- transport proteins are very specific (ex. Na+ channels, K+ channels)
27
active transport - types
- primary active transport
- secondary active transport
- exocytosis
- endocytosis
28
primary active transport
type of active transport
- gets en- from hydrolysis of ATP
- solutes pumped against their concentration gradient by membrane proteins
- ex. Na+/K+ pump
29
secondary active transport
type of active transport
- aka co-transport
- gets en- from released en- of exergonic reaction (flow of another solute down its concentration gradient)
- symportes: molecules that move two solutes in the same direction
- antiporters: molecules that move two solutes in opposite directions
30
symporters
- found in secondary active transport
| - are molecules that move two solutes in the same direction
31
antiporters
- found in secondary active transport
| - are molecules that move two solutes in the opposite direction
32
transport of big molecules
active type of transport
- exocytosis
- endocytosis
33
exocytosis
- active type of transport
- movement of large molecules or particles out of the cell (requires en-)
- membrane-bound vesicle fuses with the membrane and expels its contents
34
endocytosis
- active type of transport
- movement of large molecules or particles to the inside of the cell
- membrane folds inwards, trapping material from the outside
- can be: receptor-mediated, phagocytosis, pinocytosis (bulk-phase endocytosis) and transcytosis
35
types of endocytosis
- receptor-mediated
- phagocytosis = cell eating
- pinocytosis (bulk-phase phagocytosis) = cell drinking
- transcytosis
36
transcytosis
movement of a substance through a cell as a result of endocytosis and exocytosis on the opposite side of the cell
37
osmosis
- movement of water across a selectively permeable membrane
- water diffuses across a membrane from the region of lower solute concentration to the region of higher solute concentration
38
osmolarity of cell
- isotonic solution
- hypotonic solution
- hypertonic solution
39
isotonic solution
equal solute concentration to the inside of the cell
| - water moves in and out of the cell
40
hypotonic solution
lower solute concentration than the inside of the cell
- water moves into the cell
- rbc: hemolysis
41
hypertonic solution
higher solute concentration than the inside of the cell
- water moves out of the cell
- rbc: crenation
42
cytosol
- fluid and solutes
| - in cytoplasm
43
organelles
- subcellular structures
| - in cytoplasm
44
cytoskeleton
- network of fibers that runs throughout the cell
1. microfilaments
2. intermediate filaments
3. microtubules
- functions:
1. establishes and maintains cell shape
2. provides mechanical strength
3. locomotion
4. chromosome separation during cell division
5. intracellular transport of molecules
45
cytoskeleton - functions
1. establishes and maintains cell shape
2. provides mechanical strength
3. locomotion
4. chromosome separation during cell division
5. intracellular transport of molecules
46
cytoskeleton - types of fibers
- microfilaments
- intermediate filaments
- microtubules
47
microfilaments
- composed of double-twisted filaments of actin
| - function: control cell shape and movement
48
intermediate filaments
- composed of several different fibrous proteins depending on cell type
- function: reinforces cell and anchors certain organelles
49
microtubules
- straight hollow tubes composed of globular protein called tubulin
- functions:
1. give cell rigidity and shape
2. provide anchors for organelles
3. act as tracks for organelle movement and migration of chromosome during cell division
4. cilia and flagella
50
centrosome
- is a microtubule organizing centre
- consists of a pair of centrioles (composed of microtubules arranged in a circular pattern of 9 triplets) and pericentriolar matrix
- function: organize spindles for chromosome migration during cell division
51
cilia and flagella
- locomotor appendages that protrude from some cells
| - made of microtubules covered by plasma membrane
52
cilia
- locomotor appendages that protrude from some cells
- made of microtubules covered by plasma membrane
- perpendicular movement
- many and short
53
flagella
- locomotor appendages that protrude from some cells
- made of microtubules covered by plasma membrane
- drives cell forward
- single, long
54
ribosomes
- particles made of rRNA and protein
- composed of a large and a small subunit, which are made in nucleolus, and assembled in cytoplasm
- carry out protein synthesis
- found free in cytosol or bound to ER (make rough ER)
55
ER
- two types based on presence/absence of ribosomes: rough (with) and smooth (w/o)
- interior space is distinct from cytoplasm
56
rough ER
- continuous with nuclear envelope and makes membrane and proteins
- has ribosomes: makes secretory proteins, membrane proteins and organellar proteins
57
smooth ER
- extends from rough ER
- synthesizes lipids, fatty acids and steroids
- stores glycogen and calcium in specialized cells
- in some cells: regulate carbohydrate metabolism and breaks down toxins and drugs
58
golgi complex
- stacks of membranous sacs
- receive and modify products from ER, then sends them on to the other organelles or to the cell membrane
- function: modify, sort, package and prepare proteins for their final destination
59
rough ER - function
has ribosomes: makes secretory proteins, membrane proteins and organellar proteins
60
smooth ER - function
- synthesizes lipids, fatty acids and steroids
- stores glycogen and calcium in specialized cells
- in some cells: regulate carbohydrate metabolism and breaks down toxins and drugs
61
golgi complex - function
modify, sort, package and prepare proteins for their final destination
62
lysosomes
- sacs of digestive enzymes budded off the golgi complex
- digest cell's food and wastes by hydrolyzing proteins, fats, polysaccharides, and nucleic acids
- acidic pH
63
lysosomes - function
digest cell's food and wastes by hydrolizing:
- proteins
- fats
- polisaccharides
- nucleic acids
64
mitochondria
- sites of cellular respiration
- involved in apoptosis
- harvest chemical en- from food and store it in the form of ATP (en- molecule of cell)
- double membrane: inner-membrane arranged in folds called cristae
65
cellular respiration - purpose
- to release en- in food molecules in a gradual and controlled manner
- allows en- to be captured and harnessed to perform work
- glucose + O2 ---> CO2 + H2O + ATP
66
cellular respiration - parts
- glycolysis: breaks apart glucose
- citric acid cycle: makes e- carriers (e- have lots of en- stored in them)
- oxidative phosphorylation: takes en- of e- and uses it to pump protons (H+) which in turn rotate the ATP synthase to make ATP
67
glycolysis
breaks down one glucose molecule into 2 pyruvates, storing e- (en-) in e- carriers
68
citric acid cycle
each pyruvate breaks down into 3 CO2 molecules and e- are stored in e- carriers (NADH and FADH2)
69
oxidative phosphorylation
- e- carriers feed e- into e- transport chain
- series of redox reactions gradually release en- that is used to pump protons across the mitochondrial inner membrane
- protons flow back across membrane down their concentration gradient through ATP-sythase enzyme and power phosphorylation of ADP to make ATP
70
nucleus
- largest and most prominent organelle
- is cell's genetic control centre as it directs protein synthesis (allows it to control cell activity)
- separeated from cytoplasm by nuclear envelope
- perforated with nuclear pores that regulate entry and exit of material
- contains nucleus and chromatin
71
nucleolus
- region in nucleus where rRNA is synthesized
- cluster of DNA and RNA
- not membrane bound
72
chromatin
- found in nucleus
- composed of DNA and associated histone proteins
- condenses into chromosomes during cell division
73
gene
- hereditary units of DNA that contain info to build a specific protein
- different gene expressions
74
DNA
informational molecule: set of instructions for cell
75
central dogma of molecular biology
DNA ---> transcription ---> mRNA ---> translation ---> protein
76
transcription takes place in ___ and translation takes place in ___
- nucleus
| - ribosomes (cytoplasm or rough ER)
77
genetic code
- sequence of nucleotides determines sequence of aa along polypeptide chain
- codon: 3 nucleotides that code for 1 aa
78
codon
3 nucleotides that code for 1 aa
79
transcription
- genetic info encoded in DNA is copied onto a strand of mRNA using complementary base paring
- RNA polymerase binds to promoter
- RNA nucleotides are added complementary to one strand of DNA
- RNA polymerase detaches at terminator sequence
80
mRNA processing
- transforms pre-mRNA into mature mRNA
- add 5' cap and 3' poly-A-tail
- RNA splicing: introns in pre-mRNA are cut out and exons are pasted together to form mRNA
81
introns
- intervening sequence (not expressed)
| - cut out from pre-mRNA during mRNA processing
82
exons
- expressed (code for protein)
| - pasted together to form mRNA in mRNA processing
83
translation
- after mRNA has been transcribed and sliced, it is converted into a protein
- mRNA is read by a ribosome, which assembles the appropriate amino acids into a protein
- each mRNA codon specifies the next aa to be added to the chain (AUG - Methionine: start codone)
- tRNA bring aa to ribosome (anticodon on tRNA base-pairs wich complementary codon on mRNA)
- ribosomes catalyze formation of peptide bond btw aa until they reach stop codon
84
AUG
- methionine
| - start codon
85
stages of translation
- initiation
- elongation
- termination
86
cell division - types
- somatic cell division
| - reproductive cell division
87
somatic cell division
- body cells divide
- purpose: to increase number of body cells (for growth or replacement of damaged cells)
- 1 cells splits and becomes 2 cells: the 2 daughter cells are identical to the parent cell
- nuclear division = mitosis
- cytoplasmic division = cytokinesis
88
reproductive cell divison
- only for production of gametes (oocytes and sperm)
- produce daughter cell with half the genetic material of parent cell
- parent cell: 23 pairs of homologous chromosomes - diploid ---> 46 chromosomes
- daughter cell: 23 chromosomes not paired - haploid
- nuclear division: meiosis (2 successive nuclear divisions)
- cytoplasmic division = cytokinesis
89
somatic cell cycle
- interphase: cell carries out early life processes except division (G1, S and G2 phase)
- mitotic phase: cell division
90
interphase
- cell has distinct nucleus and chromosomes are not visible b/c DNA not condensed
- S phase: DNA replicates to produce 2 copies of each chromosome
- same number of chromosomes but duplicated (sister chromatids)
- from 46 unduplicated chromosomes to 46 duplicated chromosomes
91
S phase
in interphase: DNA replicates to produce 2 copies of each chromosome
- same number of chromosomes but duplicated (sister chromatids)
- from 46 unduplicated chromosomes to 46 duplicated chromosomes
92
mitosis
- occurs when nuclus of a cell divides
- results in distribution of 2 sets of chromosomes into 2 separate nucleui (duplicated ---> unduplicated)
- 4 steps: prophase, metaphase, anaphase, telophase
93
mitosis - steps
- prophase
- metaphase
- anaphase
- telophase
94
prophase
- step 1 of mitosis
- chromatin condenses into visible chromosomes
- pair of identical chromatids held together by centromere
- nucleolus disappears
- nuclear envelope breaks down
- cell has 23 pairs of duplicated chromosomes (46 tot)
95
metaphase
- step 2 of mitosis
| - centromeres line up at exact centre of mitotic spindle: at metaphase plate/equatorial plane
96
anaphase
- step 3 of mitosis
- separation of centromeres
- two sister chromatids move toward opposite poles of cell
97
telophase
- step 4 of mitosis
- cleavage furrow forms
- chromosomes uncoil and revert to chromatin
- nuclear envelope reforms
98
cytokinesis
- division of cytoplasm and organelles
| - process begins in late anaphase or early telophase with formation of cleavage furrow
99
meiosis
- reproductive cell division
- produces haploid cells with 23 chromosomes
- occurs in 2 consecutive stages: meiosis I and meiosis II
100
meiosis I
pairs of homologous chromosomes become single chromosomes
| - chromosome # reduced by half
101
meiosis II
- duplicated chromosomes become unduplicated chromosomes
102
meiosis I - prophase I
- chromosomes arranged in homologous pairs to from tetrads (2 versions of each 23 duplicated chromosomes)
- crossing over: tetrads exchange genetic material to create genetic diversity
103
crossing over
- in meiosis I of prophase I
| - tetrads exchange genetic material to create genetic diversity
104
meiosis I - metaphase I
- homologous pairs line up along metaphase plate
| - homologous chromosomes are side by side
105
meiosis I - anaphase I
members of each homologous pairs separate, with one member of each pair moving to an opposite pole of the cell
106
meiosis I - telophase I + cytokinesis
- similar to telophase and cytokinesis of mitosis
| - result: each cell is haploid (only 23 chromosomes)
107
meiosis II
- steps similar to mitosis
| - consists of: prophase II, metaphase II, anaphase II and telophase II
