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BIOLOGY-FY > S1-L7: Cell Organelles-Structure and Function > Flashcards

S1-L7: Cell Organelles-Structure and Function Flashcards

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1
Q

Define and describe the cytoplasm

A
  • contains all cellular components between memebrane AND nucleus
  • contains 2 components:
  • ->cytosol- intracellular fluid
  • ->organelles- specialised structures which co-operate to maintain homeostasis
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2
Q

Outline what the cytosol is and its function

A
  • intracellular fluid- 55% of cell’s total volume- 75-90% water
  • contains dissolved ions/ glucose/ amino acids/ ATP/ lipids AND waste products
  • site of wide range of enzymatically controlled reactions
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3
Q

Briefly explain what the cytoskeleton is and it’s function

A
  • consists of network of protein filaments extending throughout cytoplasm
  • ->helps maintain cell shape AND internal organisation
  • ->provides mechanical support- enables cell to carry out essential functions like division/ movement
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4
Q

State the 3 main protein filaments

A
  • microfilaments
  • intermediate filaments
  • microtubules
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5
Q

Outline and describe the function of microfilaments (figure 1)

A
  • help generate movement- contraction/locomotion & cell division
  • provide mechanical support needed for cell strength & shape
  • surround edge of cell
  • actin & myosin proteins
  • create microvilli- like in small intestine
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6
Q

What is the function of intermediate filaments-explain?

refer to figure 2

A
  • help stabilise positions of organelles
  • found in parts of cell subject to mechanical stress
  • ->v. strong
  • ->proteins like keratin/ vimentin & lamin
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7
Q

Describe microtubules and their function (figure 3)

A
  • long unbranched hollow tubules made from tubulin
  • ->form in centrosome & radiate outwards
  • help strengthen cell/cell shape & organelle movement like vesicles and during division
  • help provide structure to flagella- like spermatozoa
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8
Q

Outline the link between the centrosome & microtubules

A
  • during prophase centrosome associated with nuclear membrane
  • in mitosis nuclear membrane breaks down AND centrosome nucleated microtubule able to interact with chromosomes to build mitotic spindle
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9
Q

Outline what the flagellum is and it’s function

A
  • whip-like structure which allows cell to move
  • found in all 3 domains of living world- bacteria/ archaea & eukaryotes AKA protists/ animals & fungi
  • all 3 flagella types used for locomotion BUT structurally differ
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10
Q

What are microfilaments composed of? (figure 4)

A
  • made up of protein actin strands

- ->often interact with strands of other proteins

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11
Q

Describe the structure of intermediate filaments and their function (refer to figure 5)

A
  • made up of tough fibrous proteins organised in to tough rope like assemblies
  • ->stabilise cells structure AND help maintain it’s shape
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12
Q

Outline the structure of microtubules (figure 6)

A
  • long hollow cylinders made up of many molecules of protein tubulin
  • ->tubulin consists of 2 subunits: a-tubulin AND B-tubulin
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13
Q

How are the three different components of cytoskeleton linked?

A

-work in unison to provide support AND functionality

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14
Q

Summary of microfilaments/ intermediate filaments & microtubules

A

Microfilaments:
-thickest/ cell structure & cell motility (movement)/ tubulin
Intermediate Filaments:
-intermediate/ more permanent fixtures/ keratin
Microtubules:
-thinnest/internal movements/within cell/actin & myosin

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15
Q

What is the centrosome?

A
  • serves as main microtubule organising centre AND regulator of cell cycle progression
  • function- growth of mitotic spindle during cell division
  • found near nucleus
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16
Q

Outline the two centrioles the centrosome consists of

A
  • cylindrical structures composed of 9 clusters of microtubule triplets- both right angles to each other
  • pericentriolar material surrounds centrioles AND consists of numerous tubulin rings
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17
Q

How does the division process of eukaryotic cells affect the presence and function of centrosome? (refer to figure 7)

A
  • in dividing eukaryotic cell most microtubules spread out from centrosome
  • when cell not undergoing division- single centrosome present
  • ->BUT when cell begins to divide- centrosome replicates earlier on
  • ->spindle apparatus then begins to form
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18
Q

What is the function of the chromosome in the process outlined previously?

A

-chromosome function is to maintain equal distribution of chromosomes in daughter cells

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19
Q

Outline what Cilia & Flagella are

A
  • primarily made from microtubules

- ->are motile projections on cell surface

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20
Q

How are Cilia organised? (figure 8)

A
  • numerous short hair type of projections
  • each cilium anchored to basal body has core of microtubules enclosed in membrane
  • ->9 pairs of microtubules encircle central pair
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21
Q

State the function of cilia

A

-transport of fluid along cells surface

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22
Q

Explain the effect of smoking on cilia

A
  • destroys cilia-results in mucus/dust AND bacteria build up within lungs
  • ->cough persistently to remove
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23
Q

How does smoking affect pregnancy?

A
  • pass oocyte (egg) towards uterus

- ->but female smokers have increased risk of ectopic (abnormal position/not right place) pregnancy

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24
Q

What is the structure of flagella like?

A
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25
Q

Where are each of the following found?: (refer to figure 9)

1-Cilia
2-Flagella
3-Microvilli

A

1-found on ciliated epithelial cells like in lungs
–>wave rhythmically to move dirt + mucus
2-found on some bacteria AND allow them to swing
3-found in small intestine AND increases S. Area for nutrient absorption

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26
Q

Define what the endoplasmic reticulum (ER) is

A

-ER is network of membranes in form of flattened s\cs AND tubules extending from nuclear envelope in to cytoplasm

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27
Q

What are the two types of endoplasmic reticulum’s?

A
  • rough ER

- smooth ER

28
Q

Outline the structure & function of the rough ER (refer to figure 11)

A
  • rough ER has ribosomes attached- site of protein synthesis
  • proteins made by ribosomes enter ER space for processing AND sorting (“factory”)
  • enzymes may attach carbohydrate groups/ proteins to phospholipid
  • ->these molecules may be incorporated into membrane of organelles OR plasma membrane OR secreted via exocytosis
29
Q

Describe the structure of ribosomes (figure 12)

A
  • consists of large subunit AND small subunit synthesised separately in nucleolus
  • are rich in ribosomal RNA (information) AND contain 50+ proteins each
30
Q

Where may ribosomes be found?

A
  • may be present free in cytoplasm

- ->within mitochondria OR attached to endoplasmic reticulum

31
Q

State the function of ribosomes

A

-site of protein synthesis

32
Q

Describe the smooth ER

A
  • extends from rough ER

- contains no ribosomes BUT has greater enzyme range–>making its function more diverse

33
Q

What is the function of the smooth ER?

A
  • synthesises fatty acids & steroids like oestrogen plus testosterone
  • in liver helps release glucose from fluc-6-p & detoxify lipid soluble drugs like alcohol AND pesticides
  • sores Ca2+ ions in muscle
34
Q

Explain the effect of repeatedly taking drugs on the ER

A
  • individuals repeatedly taking drugs like sedative phenobarbital
  • ->develop changes in smooth ER in liver cells
  • ->cells produce more smooth ER to counteract poison- means person has to take more of drug to feel it’s effect
35
Q

Outline the structure of the golgi complex (refer to figure 13)

A
  • consists of 3-20 membranous cisternae (sac like structures) with bulging edges arranged in stack
  • ->entry (or cis) face faces ER AND exit (trans) face faces plasma membrane
  • ->in between sacs called medial cisternae
36
Q

What is the link between the golgi complex and the ER?

A

-most proteins from rough ER transported to other regions of cell including golgi complex

37
Q

What is Retrograde transport?

A

-refers to motion from periphery (outside boundary) of cell to centre

38
Q

Outline the processing & packaging process steps by the golgi complex (refer to figure 14)

A

1-transport vesicles containing polypeptide bud off smooth ER
–>fuse with cis face of golgi apparatus
–>releasing polypeptide into lumen of golgi apparatus
2-processing through golgi complex occurs
3-polypeptide packaged in to vesicle released from trans side
–>secretory vesicle releases polypeptide via exocytosis
–>secretory vesicle may become lysosome
-membrane protein attached to a vesicle–> this vesicle inserted into plasma membrane

39
Q

What is the function of lysosomes? (figure 15)

A

-digestion of substances entering cell/ worn out organelles (autography) AND entire cells (autolysis)

40
Q

What is autography required for? (figure 16)

A

-for renewal/ cellular differentiation/ control of growth AND tissue modelling

41
Q

Outline what Tay-Sachs disease is

A
  • inherited condition affecting children- caused by lysosomal enzyme Hex A mutation
  • ->normally breaks down glycolipid ganglioside GM2-especially in prevalent cells
42
Q

Explain the effect of the enzymes absence that causes the Tay-Sachs disease (refer to figure 17)

A
  • in enzyme absence glycolipid builds up–> destroying nerves cell function
  • ->patient suffers from seizures/ muscle rigidity AND becomes blind
  • ->death occurs before age 5
43
Q

State and explain the function of peroxisomes

A
  • involved with amino acids AND fatty acid metabolism
  • oxidise toxic substances like alcohol- high copy number in liver
  • also contain enzyme catalase to protect against toxic effect of hydrogen peroxide (made in oxidation reactions)
  • contains oxidases/similar to lysosomes BUT smaller
44
Q

What are peroxisomal disorders?

A
  • form heterogeneous disease group with different degrees of severity
  • ->are metabolic disease- these share dysfunction of peroxisomes
  • ->all lead to brain disorders & respiratory infections
45
Q

Outline how fatal each of the following peroxisomal disorders are:

1-Zellweger Syndrome (ZS)
2-Neontal adrenoleukodystrophy
3-Rhizomelic chondroysplasia punctata (RCDP)

A

1-usually fatal within first year of life
2-usually fatal within first 10 years
3-most sever form in first 2 years of life

46
Q

When may metabolic disorders happen?

A

-can happen when abnormal chemical reactions in body alter normal metabolic process

47
Q

Define what proteasomes are and their importance

A
  • lysosomes which specifically degrade proteins (unneeded/damaged or faulty)
  • contain protease enzymes
  • important in negative feedback–>switch off pathway once response achieved
48
Q

How many proteasomes does a typical cell contain?

A

-thousands of these structures but they have only bee recently discovered

49
Q

What causes Alzheimer’s disease and is there any possible cure?

A
  • caused by misfolded proteins (in brain) building up
  • on-going research to look at why these proteins not degrades
  • ->possible cause is proteasome dysfunction
50
Q

Outline the function of the mitochondria

A
  • aerobic respiration site–>converts glucose to produce energy (from ATP)
  • ->3 main steps to process: glycolysis/ citric acid cycle AND Krebs cycle & ATP synthesis
  • “power house of cell”
  • cells have 100-1000’s depending on function
  • other functions: signalling/ cell differentiation/ cell death
51
Q

What is the structure of the mitochondria?

A

-2 membranes made of phospholipids double layer + proteins–>both have different properties

52
Q

What are the 5 distinct compartments within mitochondrion?

A
  • outer mitochondrial membrane
  • intermembrane space–>space between outer AND inner membranes
  • inner mitochondrial membrane
  • cristae & matrix (space within inner membrane)
  • ->cristae provide v. big S.A for respiration
  • ->enzymes needed for respiration found in matrix on cristae
53
Q

State how the following parts of the mitochondria are adapted for their function (refer to figure 18)

1-Intermemebrane space 
2-Inner membrane space 
3-Cristae 
4-Matrix 
5-Outer membrane
A

1-small space to quickly accumulate protons
2-contains ETC and ATP synthase for oxidative phosphorylation
3-highly folded to increase SA:V ratio
4-has appropriate enzymes AND suitable pH for Kreb’s cycle
5-contains transport proteins for shuttling pyruvate into mitochondrion

54
Q

What may be the cause of mitochondrial disease?

A
  • disorders caused by dysfunctional mitochondria
  • sometimes caused by mutations in mitochondrial DNA- affect mitochondrial function
  • mutations in genes of nuclear DNA-whose gene products imported into mitochondria (mitochondrial proteins) & acquired mitochondrial condition
55
Q

Why do mitochondrial diseases take on unique characteristics?

A
  • due to way disease often inherited

- also as mitochondria very critical to cell function

56
Q

State some of the symptoms/problems experienced from mitochondrial disease

A
  • poor growth
  • muscle co-ordination loss
  • visual problems
  • hearing problems
  • heart/liver disease
  • respiratory disease
  • dementia
57
Q

Outline some of acquired conditions in which mitochondrial dysfunction has been involved

A
  • diabetes
  • Huntington’s disease
  • cancer
  • bipolar disorder
  • anxiety disorders
  • cardiovascular disease
58
Q

What is the basic structure of the nucleus?

A
  • spherical/oval shaped & most cells have one

- surrounded by double membrane (nuclear envelope)

59
Q

How are the structures of the nucleus adapted for it’s functions?

A
  • many nuclear pores extended throughout envelope
  • ->channels for ions. A. transport for RNAs & proteins
  • in centre spherical bodies called nuclei present
  • clusters of proteins/DNA + RNA
  • ->responsible for producing ribosomes
60
Q

Define the term Chroatin and outline it’s function

A
  • complex of DNA + protein found in eukaryotic cells

- ->primary function- packaging long DNA molecules into compact AND denser structures

61
Q

What is transcription?

A
  • process of constructing messenger RNA molecule using DNA molecules as template with resulting transfer of genetic info to messenger RNA (conveys message)
  • happens in nucleus
62
Q

Outline how the first process (transcription) occurs (figure 19)

A
  • DNA separates into two complementary strands

- mRNA makes copy of DNA

63
Q

What is translation?

A
  • mRNA formed in transcription transcribed out of nucleus in to cytoplasm to ribosome (cell’s protein synthesis factory)
  • ->here directs protein synthesis and this process occurs in rough ER/ cytoplasm
64
Q

How does the second process of translation occur? (figure 19)

A
  • mRNA bonds with ribosomes at start of codon
  • ->tRNA brings amino acids to polypeptide
  • ribosome reads codons AND assembles amino acids in order
  • stop codon releases polypeptide AND ribosome
65
Q

Outline how everything discussed in this lecture comes together

A

-observe figure 20 to understand the process

BIOLOGY-FY (12 decks)

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