1.7-1.8: Ribosomes, ER and Golgi; Mitochondria and Cytoskeleton Flashcards
1
Q
Where is the information for the sequence of protein contained?
A
within the mRNA generated during transcription
2
Q
Protein synthesis is
A
the assembly of polypeptides through a process called translation
3
Q
Difference between use of proteins produced by free ribosomes and ribosomes on the rER
A
Generally, proteins produced by free ribosomes are for use by the cell itself, which do not require further processing by the rER and typically don’t go through the golgi;
proteins produced in the rough ER are for export (only ones for export goes to rER), or are housed within membrane-bound
vesicles.
4
Q
what happens to the mRNA after leaving the nucleus through its nuclear pores?
A
- transcription occurs, dna strand formed template, mrna strand forms, forms pre-mrna strand with introns. remove introns then have mrna
- leaves nucleus via pores
either goes to free ribosomes (may form collection of free ribosomes called polyribosomes with polybackbone being made - or associates with rer where mRNA stand gets read and peptide goes into membrane instead of cytoplasm
5
Q
Describe structure of a ribosome after the mRNA has arrived.
A
- small subunit clamps onto the mRNA strand, and the large subunit attaches itself onto it.
- there are little spaces for trna to come along, recognise codon and attach amino acid to polypeptide sequence.
6
Q
ribosome structure diagram fill in
A
photos
7
Q
there is a different _____ for each amino acid
A
tRNA
8
Q
three steps of mRNA being translated into protein
A
- initiation: tRNA binds onto codon to pair with its anticodons
- elongation as more amino acids are added to strand
- termination: stops production of protein, modified within ER
9
Q
What is the amino acid represented by the first codon? (always)
A
Methionine (Met) is always the first amino acid in a polypeptide chain.
10
Q
ER diagram fill in
A
photos
11
Q
ER occupies how much of the total membrane volume of the cell?
A
half the total membrane volume of cell
12
Q
A
system of interconnected tubules and vesicles
13
Q
inner space of ER is called
A
cistern/ cisternae (plural)
14
Q
where do metabolic processes occur?
A
surface and within the cisternae of er
15
Q
functions of smooth er
A
- Synthesis of phospholipids, steroid
hormones, triglycerides - Synthesise and store glycogen in
(skeletal muscle cells and liver) - Calcium ion storage (neurons,
muscle) - Detoxification (liver)
16
Q
why is the arrangement of polypeptide chain into protein important?
A
shape reflects function, can cause problem if not shaped correctly
e.g. alzheimers
17
Q
- Post-translational protein modifications:
A
modification of proteins after it has gone through translation
e.g. Glycosylation, formation of disulphide
bonds, proteolytic cleavage
18
Q
cell image fill in
A
photos
19
Q
plasma cell as an example of structure reflects function
A
lots of er, producing lots of protein: secreting antibodies
20
Q
what is the rough er responsible for?
A
Synthesis of membrane & organelle proteins,
proteins to be secreted/exported
* Site where protein is folded to its 3D form,
subunit assembly
21
Q
Golgi apparatus diagram fill in
A
photos
22
Q
3 key functions of golgi apparatus
A
- Plasma membrane
modification and renewal - Secretion - Modifies and
packages secretions such
as proteins (from RER) and
lipids (from SER) to be
shipped to the
appropriate site - Packages enzymes (e.g. in
lysosomes) for use within
the cytosol
23
Q
where does secretion of vesicles occur on the golgi apparatus?
A
depends on where cell want to secrete, might move to top of cell for secretion
24
Q
how does the lysosome deal with the endosome?
A
releases digestive enzymes into it, remains become refuse that can be exocytosed or remains in cell if not harmful
25
summarize the secretory pathway
transciption occurs, mrna leaves via nuclear pores, binds to ribosomes, is translated, enters cistern of the rough er, goes thru smooth er, lipid synthesis maybe, little transport vesicle buds off er, fuse with cis face of golgi and migrate though stacks, modified by enzymes, bud off to form secretory vesicles, hang around to become lysosomes or exocytosed
**a better diagram is in photos
26
what is the golgi apparatus?
a set of flattened membrane discs that process newly made proteins and lipids from the endoplasmic reticulum.
27
Mitochondrial functions
- ATP generation
* Modification of steroid lipids and
hormones
* Initiate programmed cell death (apoptosis)
* Cellular differentiation, cell cycle and cell
growth
* Heat production
28
apoptosis e.g.
webbed hands, if something interferes than those cells don't die
29
example of heat generation in mitochondria
babies have lots of round adipose tissues (fat tissues) which consists of lots of mitochondria to generate heat cuz they can't regulate their own body temperature
same for polar bears who have a lot of fat for heat generation via the lots of mitochondria
30
cellular respiration is
Series of metabolic reactions that take place in cells to convert biochemical energy from
nutrients/organic molecules into energy in the form of adenosine triphosphate (ATP)
31
catabolism
Involves the breakdown of molecules into smaller
units.
Used to release energy or in some cases the smaller
units are used for anabolic reactions.
e.g. breakdown of carbohydrates to release energy,
breakdown of protein into amino acids.
= breakdown of molecules into its constituent parts and energy
32
anabolism
Building or synthesis of molecules.
Cellular maintenance and repairs, growth, secretion of
molecules, stored nutrients.
Require energy input
e.g. ATP synthesis, protein synthesis
- building constitutent parts and energy to build a full thing
33
atp consist of
a nitrogenous base: adenine
a sugar, ribose
3 phosphate groups
34
mitochondria structure diagram fill in
photos
35
structure reflect function in mitochondria example
folds increase surface area for mitochondrion to have enzymes
36
Explain in detail the process of cellular respiration.
1. glycolysis in the cytoplasm
- no need energy
- not efficient
- glucose-> pyruvate-> 2 atp
2. Krebs cycle in the mitochondrion (citric acid cycle
- pyruvate--> acetyl CoA
- requires o2
- co2 as waste product
- produces 2 atp
- main aim is to create substrate that the electron transport chain uses to produce atp
3. electron transport chain/ oxidating phosphorylation
- occurs in mitochondrion
- uses energy from breakdown of previous products to make ATP and h2o
- 24-28 atp from 1 molecule of glucose
37
can proteins, triglycerides and glycogen produce energy directly?
no.
they need to first be catabolised into amino acids, fatty acids, and glucose (respectively
38
how does energy generation from fatty acids and amino acids differ from energy generation from glucose?
uses slightly different process to go directly into krebs instead of glycolysis
39
where is energy stored in the foods we eat for energy?
Energy is stored in chemical bonds in the nutrients (glucose, amino acids, fatty acids) in the food we eat.
40
Cytoskeleton functions
- Cell shape maintenance
* Strength- enable to withstand from abrasion for some cells prone to it
* Flexibility
* Transport around the cytoplasm, e.g. vesicles, mitochondria, neurosecretory vesicles
* Cell movement, especially using actin filaments, allowing it to undergo endocytosis
* Involved in cell division- helps separate chromosomes and cells
41
3 major classes of elements
Microfilaments: (AKA actin filaments) smallest
(nm), made of actin (a multifunctional protein
Intermediate filaments: mid-sized, constructed from a number of different subunit proteins
Microtubules: largest type of filament, composed of
tubulin
42
describe the structure of microfilaments
- Made principally of actin arranged in a long spiral chain
* Networks of microfilaments found beneath cell membrane for endocytosis and movement
* Dynamic– rapidly polymerise and depolymerise (form and deform), e.g. can phagocytose bacteria really quickly
* Have a plus and a minus end
– Plus end has faster addition/removal
– Minus end slower
43
describe the structural features and how they relate to functions of intermediate filaments
- Intermediate filaments are the strongest and most durable of the cytoskeleton filaments: would have more of them if cell is located in area that is exposed to environment prone to abrasion
- They play a structural role by providing mechanical
strength: inside nucleus has them so nucleus stays in shape, also in cytoplasm
- Stabilise organelle position, provide strength/support for
cell structure
- Composed of a fibres; protein subunits vary (e.g., keratin
in epithelial cells, vimentin in fibroblasts)
44
Describe the function and structure of microtubules
- Key role in cell division, intracellular organisation, cell shape and transport
tracks for motor proteins to move cargo, power flagella and cilia
* Long, hollow tubules made of polymers of tubulin
- motor proteins carry things like mitochondria or secretory vesicles etc on top of them
45
How do motor proteins move along microtubules?
can use microtubules as tracks
- cargo= cellular cargo like organelles and secretory vesicles
- carrying smtng at top, reconnect, reconnect and brings them along
46
how do centrioles contribute in cell division?
- polymerised more tubulin (proteins that can later polymerize into long chains that form microtubules), attach to dividing chromosomes.
- When depolymerised, they pull chromosomes back so they are separated into 2 individual cells with two separate centrosomes (duplicated)
47
Describe the structure of flagella and cilia
- Slender extensions of the plasma membrane
*Microtubule structure changes from triplets of centrioles in basal body to 9 doublets at the
upper end (the axoneme).
- It also gains a central
pair of microtubules
*Dynein moves along microtubules to exert the bending motion required, resulting in spiral pattern of movement
48
pseudopodia
a temporary arm-like projection of a eukaryotic cell membrane that is emerged in the direction of movement
49
Describe the functions of microfilaments.
- central to contractile engine
* Acts as a track for myosin motor motility (role in muscle contraction)--> in striated muscles like cardiac and skeletal, causes muscle contraction, interact with myotin to slide across and pull towards each other for contraction
* Enables cells to hold and move specialised shapes;
– Involved in membrane “pinching” process in cell division
– formation of pseudopodia: moves around with polymerisation and depolymerisation quickly
- enables phagocytosis or pinocytosis
50
Explain the dynamic instability of microtubules.
Microtubules are directional, they
have a “+” and a “-” end
– plus end; grows more rapidly
– minus end; slower dynamics
* Polymerization results in growth
while depolymerisation results in
shrinking - both are rapid
51
which direction do motor proteins move towards?
Kinesins move cargo towards the plus (+) end.
* Cargo transported away from nucleus
Dyneins move cargo towards the minus (-) end.
* Cargo transported towards the nucleus
52
motor proteins and microtubule diagram fill in
photos
53
how do motor proteins interact with microfilaments?
interact with actin in microfilaments and are involved
in muscle contraction and cell division
54
what are motor proteins called?
myosin
55
what forms a centrosome?
two centrioles
56
what are centrosomes also called?
microtubule organizing centres
57
what forms a centriole?
9 triplets of microtubules
58
what are protein filaments made of?
subunits that rapidly come together or break apart
59
What is the definition of a gene?
A sequence of DNA which codes for a particular protein or functional RNA
60
Where does protein synthesis conduct transcription?
Begins on free ribosomes then either docks to rER or leaves the ribosome for cell's own function
61
What are the products of the krebs cycle?
2 ATP, Co2, NAD, NaDH
62
oxidative phosphorylation
adding P to ADP in the form of O2
63
What is the output of ATP in phosphorylation?
28-38 ATP
64
Functions of intermediate filament
- strengthen cell
- made with keratinocytes (riched with keratin, strongest protein to protect the body
- found on outside of skin
65
what's the space between layers of rough ER called?
cisternae
66
What are the processes of the smooth ER?
- synthesis and storage of glycogen and glycerides in muscle and liver cells
- detoxification of poison and drugs
- synthesis of phospholipids and cholesterol
- has enzymes that create triglycerides
- stores calcium ions
- initiation of contraction of cell
- synthesis and vesicular packaging of steroid hormones (androgens and oestrogens in reproductive cells), e.g. cortisol from adrenal glands
67
Expand on the function of synthesis and storage of glycogen and glycerides in muscle and liver cells that the smooth ER conducts.
- when there's lots of glucose, sometimes there's a hormone released by pancreas that stimulates glucose to be stuck together in a big chain called glycogen
- glycerides are especially produced as triglycerides in liver in fat cells-> if obese, patient may have fatty liver disease where liver cells are pushed out as there is too much of fat in liver which is not good for normal functioning
68
why can you find lots of sER in the egg cell?
- when sperm first bind to membrane of oocyte (a developing egg), it causes an influx of release of calcium from the ER, which then activates the oocyte to begin development and continue development
69
What is an example of a steroid hormone that smooth ER synthesize and packages?
- androgens and oestrogens in reproductive cells
- cortisol from adrenal glands
70
Why are some protein bits in a cell darker?
- eosin stain used is acidic
- attaches to protein, especially those that make up cytoskeleton
- causing them to appear as a darker colour due to its accumulation
71
where does detoxification occur in the body?
around body, intestines, liver (primary site
72
what happens to the liver as the patient chronically drinks alcohol?
cirrhosis
73
how does the sER conduct detoxification of alcohol?
- alcohol dehydrogenase within membranes of smooth ER that breaks down alcohol
- some people don't have this, resulting in alcohol intolerance
74
What organelle have their inside gaps named as cisternae?
ER, golgi
75
What do you call the gaps between layers of inner membrane in mitochondria?
Cristae
76
What is the equation of cellular respiration?
C6H12O6+ 6O2------> 6H2o+ 6CO2+ 32ATP
77
How is the body related to cellular respiration?
entire body system is designed to get rid of byproducts (e.g. h20--> peeing, co2---> exhale)
78
Where is info stored asthe DNA?
Stored as a sequence of nitrogenous bases
79
what is heterochromatin?
tightly packed, inactive chromatin
80
transaltion starts with _____ (codon that codes for a particular amino acid/ signal
AUG coding for start
81
Pentapeptide
5 amino acids in a chain
82
What order does removal of introns occur in (from which end to which end
from 5'' to 3''
83
sketch diagram of trna
photos (google
84
what does the large subunit do in a ribosome?
catalyse peptide bond
85
differentiate sense mutation and non-sense mutation.
sense: change in amino acid (little or dramatic effect)
non-sense: no change to amino acid
86
whats the difference between euchromatin and heterochromatin?
eu: loose, hetero: tight
87
what are nucleosomes?
areas of DNA wrapped around histones
88
what is a gene?
a basic unit of heredity/ inheritance
- carries the information that determines your traits
