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Medical Cell Biology 🌟 > SESSION 1 > Flashcards

SESSION 1 Flashcards

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1
Q

Define Golgi body

A

Export of proteins
Detoxification reactions

Relieves proteins/ lipids from RER 
Modifies, sorts and packs into vesicles 
Dispatched to one of three destinations:
1) within the cell to lysosomes
2) plasma membrane 
3) outside cell

Cis Golgi network- the entry area of the Golgi
Trans Golgi network- final reactions and sorting takes place

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2
Q

Define Cytoplasm

A

Metabolism of carbohydrates, amino acids and nucleotides

- fatty acid synthesis

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3
Q

Define Lysosomes and their functions

A

Cellular digestion

Functions:
- release enzymes outside of the cell (exocytosis)
- digestion of materials from inside the cell (autophagy)
- digestion of materials from outside the cell
(Heterophagy)
- recycle products of biochemical reactions - materials brought back into the cell (endocytosis)
- completely break down cells that have died (autolysis)

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4
Q

Define mitochondria

A

ATP synthesis by oxidative phosphorylation

Mitochondria contain their own genetic information that can divided- maternal linage

Double membrane
Inner membrane folded into cristae

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5
Q

Define endoplasmic reticulum

A

Export of proteins

  • membrane synthesis
  • lipid and steroid synthesis
  • detoxification reactions
  • protein synthesis (RER)
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6
Q

Define nucleus

A

DNA synthesis and repair

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7
Q

Define nucleolus

A

RNA processing and ribosome assembly

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8
Q

Define plasma membrane

A

Cell morphology and movement

- transport of ions and small molecules

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9
Q

Define ribosome

A

Protein synthesis

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10
Q

List the principal differences between prokaryotic and eukaryotic cell

A

Prokaryotic cells lack a nucleus and other membrane bound organelles, other than a ribosome
Consists of one circular strand of DNA
Their cytoskeleton is flagella only
They also have a cell wall

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11
Q

How can the differences in prokaryotic and eukaryotic cell structure and function be exploited by medicine?

A

The cell wall can be targeted by drugs such as antibiotics, which will not affect eukaryotic cells in the same way

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12
Q

Discuss the bonds important for macromolecular structure and interaction

A

Monomeric units are joined together by covalent bonds to form macromolecules
Macromolecules are held together by non- covalent interactions:

  • hydrogen bonds: from between a hydrogen atom bound to an electronegative atom and another electronegative atom
  • ionic interactions- can be attraction of repulsion depending on barge
  • hydrophobic interactions: non- polar. Won’t interact with water, e.g. Lipids. Good for storage, bilayer
  • van der waals interactions: any two atoms in close proximity
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13
Q

Explain the difference between hydrophobic and hydrophilic molecules

A

Hydrophobic- will not interact with water, e.g. Lipids, storage without water and can pass through lipid bilayers

Hydrophilic- polar, interact with water. Reduces storage ability (e.g. Glycogen)cannot pass through lipid bilayers unassisted

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14
Q

Explain what is meant by amphipathic

How can these molecules form a lipid bilayer?

A

It has both hydrophobic and hydrophilic parts on the same molecule

When immersed in water, they arrange themselves so hydrophilic heads are exposed and hydrophobic tails are contained internally

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15
Q

Explain the concept of pH, pK and buffers

A

PH:
A measurement of the concentration of H+ ions in a solution.
- strong acids and bases completely dissociate in solution
- weak acids and bases barely dissociate

PK:
The stronger the tendency of an acid to dissociate the lower the pKa value

Buffers:
Mixtures of a weak acid and its conjugate base which resist changes in pH

When pH> pK the deprotonated dominates
When pH < pK the protonated form dominates
When pH = pK the amount of acid and its conjugate base is equal

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16
Q

How do you calculate the concentration of H+ ?

A

PH= -log[H+]

H+ = 10^-pH

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17
Q

Classify amino acids according to the properties of their R groups

A

AA’s can be classified by:

  • their interaction with water at a pH of 7
  • the charges of their side chains at a pH of 7

AA’s with benzene rigs are described as aromatic, without are aliphatic

Nonpolar, aliphatic/ polar, uncharged/ aromatic/ positively charged/ negatively charged

18
Q

Explain how the charge on amino acids are affected by pH

A

A zwitterion is a neutral molecule that has both positive and negative charge
When pH > pKa of an AA, it becomes deprotonated and vice versa

19
Q

Explain how AA charge can influence the isoelectric point of a protein

A

PI- the isoelectric point is the pH at which the protein has no overall charge

Acidic proteins (low pH) contain many negatively charged amino acids and have a low pI 
Basic proteins (high pH) contain many positively charged amino acids and have a high pI
20
Q

Why do metabolically active tissues cause a fall in blood pH?

A

During metabolic activity many acidic byproducts, e.g. Lactic and carbonic acid, are produced lowering pH

This is true of aerobic as well as anaerobic conditions

21
Q

Explain how a peptide bond is formed and list its key features

A
  • AA’s are covalently bound to one another via a peptide bond that forms between the carboxyl group of one AA and he amino group of a second
  • peptide bond formation is a condensation reaction - releases H2O
  • all atoms of the bond are in the same plane
  • there is no rotation about the peptide bond due to double bond characteristics
  • carbonyl oxygen and aside hydrogen are in the trans orientation
22
Q

Explain how rapid breathing ((hyperventilation) can cause an increase in blood pH

A

More CO2 is lost
Decrease in carbonic acid
Therefore there is an increase in pH as there is less acid

23
Q

What effect would a pulmonary obstruction have on blood pH?

A

A pulmonary obstruction would decrease the pH as there is a build up of CO2

24
Q

Explain how DNA is packaged

A

147 base pairs of DNA is wrapped around 8 histones to form the basic chromatin unit- the nucleosome
Looped further into a structure called a solenoid
Coiled again into a tightly packed structure- chromosome

25
Q

What is the role of chromatin?

A

Allows mitosis and meiosis
Prevents chromosome breakage
Controls gene expression
Controls DNA replication

26
Q

Define euchromatin

A

chromosome material which does not stain strongly

27
Q

Define heterochromatin

A

chromosome material of different density from normal - stains darker

28
Q

Define fluid mosaic model

A

Lipid bilayer

Proteins embedded in the bilayer

29
Q

What are the functions of the plasma membrane?

A
  • selective permeability
  • transport of materials along cell surface
  • endocytosis
  • exocytosis
  • intracellular adhesion
  • intercellular recognition
  • signal transduction
30
Q

Define glycocalyx

Give examples within the body

A

A thick, sticky outer covering of the plasma membrane
Composed of strand of sugars and proteins bound together

Two examples:
- blood vessels:
Endothelial cells withstand the stress of blood flowing over them constantly
Glycocalyx helps important vascular cells adhere to blood vessels, such as leukocyte and thrombocytes, which are involved in blood clotting

  • small intestine:
    Made up of microvilli that are covered with glycocalyx
    Chyme- liquid from the stomach, which is acidic flows over the microvilli
    Therefore cells need extra protection
31
Q

What is the role of the smooth ER?

A

Involved in the synthesis of lipids, including cholesterol and phospholipids, which are used in the production of new cellular membrane

Plays an important role in the synthesis of steroid hormones from cholesterol

Contributes to the detoxification of drugs in the liver

32
Q

What is the role of the Rough ER?

A

Ribosomes on rough ER specialise in the synthesis of proteins that possess a signal sequence that directs them specifically to the ER for processing

33
Q

How are lysosomes formed?

A

The Golgi apparatus forms tiny vesicles that separate from the ends of the Golgi cisternae
Vesicles formed in this way that contain enzymes such as protease and lipase, are primary lysosomes
Secondary lysosomes are formed when primary lysosomes fuse with other membrane- bound vesicles

34
Q

Define peroxisome and its functions

A

Small organelle in the cytoplasm
Contains reducing enzyme catalase and some oxidases

Functions:

  • breakdown of very long chain fatty acids through beta- oxidation
  • detoxify a number of molecules, e.g. Alcohol in the liver and kidney
35
Q

Describe the structure of cytoskeleton microtubules

A

Microfilaments, intermediate filaments and microtubules combine to form cytoskeleton

36
Q

Define actin filament

A

Made of globu;ar actin subunits
Occur as microfilaments

Important for:

  • cell shape
  • muscle contraction
  • cell adhesion
37
Q

What is the role of intermediate filaments?

A

From tough supporting mesh work in cytoplasm

Common in epithelial cells

38
Q

What is the structure of cilia or flagellum?

A

Consists of microtubules in a non- fold radial symmetry called axeoneme
Consists of 11 longitudinal fibrils, 2 central and 9 peripheral
The two central microtubules are similar in structure to cytoplasmic microtubules
The 9 peripheral fibrils are doublet microtubules, appearing like a figure of 8 in transverse section

39
Q

Which cell types are likely to obtain abundant SER, lysosomes, RER, mitochondria and perioxisomes?

A

Totes, macrophages, exocrine pancreatic cells, cardia muscle cells, kidney tubule cells

40
Q

Name four enzymes secreted by pancreatic exocrine cell and state the destination of these enzymes

A

Amylase, protease, pancreatic lipase and elastase

Intestinal duodenum

41
Q

What cellular function is facilitated by cytoplasmic extensions and lysosomes?

A

Communication with neighbouring cells, for movement and for specialised processes like wound healing

Lysosomes contain acid hydrolysed, dude with the phagosome to form a phagolysosome where they release their contents which digest the contents of the bacteria

Medical Cell Biology 🌟 (15 decks)

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