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Phase 1 Med > IMMS 1 > Flashcards

IMMS 1 Flashcards

1
Q

Describe the structure and function of mitochondria

A
  • Aerobic respiration, synthesis of ATP.
  • Double membrane.
  • Contains ring of maternal DNA.
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2
Q

Describe the structure and function of rough endoplasmic reticulum

A
  • Interconnected cisternae with ribosomes on external surface.
  • Protein synthesis.
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3
Q

Describe the structure and function of smooth endoplasmic reticulum

A
  • Same as rER without ribosomes.

- Makes and transports lipids.

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4
Q

Describe the structure and function of golgi apparatus

A
  • Made of ER.
  • Modifies and packages proteins by adding sugars, then secretes them in vesicles via exocytosis.
  • Proteins enter in cis side and leave through trans side.
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5
Q

Describe the structure and function of vesicles

A
  • Storage.
  • Transport.
  • Exchange.
  • Some e.g. lysosomes break down waste. pH around 5.
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6
Q

Describe the structure and function of cytoskeleton

A
  • Supports cell.
  • Microfilaments made of actin.
  • Microtubules made of tubulin.
  • Intermediate filaments vary from cell to cell.
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7
Q

Describe the structure and function of the nucles

A
  • Contains DNA.
  • Double membrane.
  • Contains nucleolus.
  • Produces rRNA.
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8
Q

Describe the structure and function of the cell membrane

A
  • Compartmentalisation.
  • Barrier from outside.
  • Controls what enters/ leaves cells.
  • Is a phospholipid bilayer.
  • Semipermeable.
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9
Q

List and describe the components of a cell membrane

A
  • Phospholipids (hydrophilic head, hydrophobic tail)
  • Cholesterol for stability/fluidity.
  • Glycoproteins (protein with carbohydrate chain).
  • Glycolipids (lipids with carbohydrate chain).
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10
Q

List and describe the proteins in the cell membrane

A
  • Channel proteins: Pores for water-soluble molecules.

- Carrier proteins: Change shape to allow passage of molecules.

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11
Q

List and describe different types of anchors in cells

A
  • Tight junction: Seals neighbouring cells to prevent leakage.
  • Adherent junction: Joins actin bundles in neighbouring cells.
  • Desmosome: Joins intermediate filaments in neighbouring cells.
  • Gap junction: Allows electrical activity.
  • Hemidesmosomes: Anchors intermediate filaments to basal lamina.
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12
Q

Describe endocytosis and list the three types

A

Active process to engulf molecules into a cell.

  • Phagocytosis (solids)
  • Pinocytosis (liquids)
  • Receptor mediated
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13
Q

Describe exocytosis

A

Active process to remove molecules from a cell

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14
Q

Describe diffusion

A

Passive movement of molecules from high to low concentration, down a gradient.

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15
Q

Describe facilitated diffusion

A

Passive movement of molecules using carrier or channel proteins, down a gradient.

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16
Q

Describe active transport

A

Active process working against a gradient

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17
Q

Describe three energy stores within cells

A

Lipids, licofuscin and glycogen.

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18
Q

Define homeostasis

A

Maintaining a constant internal environment

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19
Q

List and describe the three types of cell communication

A
  • Autocrine: Cell communicating with self e.g. immunity
  • Paracrine: Cell communicating with nearby cells e.g. synpases, NMJ, clotting cascades.
  • Endocrine: Cells communicating with distant cells. Slow acting and long lasting e.g. hormones - pituitary, thymus etc.
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20
Q

Describe the structure and action of peptide hormones

A
  • Proteins/ short chain amino acids
  • Fast acting
  • Large and hydrophilic so cannot pass through membranes
  • This means they have extracellular receptors
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21
Q

Describe the structure and action of steroid hormones

A
  • Synthesised from cholesterol
  • Lipid soluble, so cross membrane using transport proteins.
  • This means it has an intracellular receptor: Travels in blood bound to carrier proteins and acts directly on nucleus.
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22
Q

Describe the structure and action of amino acid derivatives

A
  • Synthesised from tyrosine
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23
Q

What % and L of water is distributed through the body?

A

42L (60%)

Intracellular - 28L (40%)
Extracellular - 14L (20%) - 11L interstitial
3L plasma

24
Q

Define osmosis

A

Process by which water molecules pass through a semipermeable membrane from an area of high to low water potential.

25
Q

Define osmolality

A

Measure of number of dissolved particles per Kg of solvent

26
Q

Define osmolarity

A

Measure of number of dissolved particles per L of solvent

27
Q

Define osmotic pressure

A

Pressure applied to a solution, by a pure solvent, to prevent inward osmosis

28
Q

Define oncotic pressure

A

A form of osmotic pressure exerted by proteins. Tends to pull water into a solution

29
Q

Describe the role of ADH in water homeostasis

A
  • Low water volume = inc. osmolarity.
  • Causes water to move out of osmoreceptors (in AV3V area of hypothalamus), towards the higher solute concentration, via aquaporin 1.
  • This causes osmoreceptors to shrink, triggering an action potential.
  • This AP triggers the supraoptic nucleus of the hypothalamus to release ADH.
  • Secreted from posterior pituitary and acts on collecting ducts of kidney. (Binds to V2 receptors on basolateral surface.)
30
Q

Describe the RAAS system

A

Renin-angiotensin-aldosterone system:

  • Macula densa of kidney detects low blood pressure or sodium concentration.
  • Renin produced by granular cells in JGA converts angiotensinogen into angiotensin I.
  • This circulates in blood until it reaches the lungs where ACE converts it into angiotensin II.
  • Angiotensin II then acts directly on blood vessels, the adrenal gland (to increase release of aldosterone, which increases sodium re-absorption), and causes an increase in the release of ADH.
31
Q

What is the most common intracellular electrolyte?

A

Potassium (K)

32
Q

What are the most common extracellular electrolytes?

A

Sodium (Na), Chloride (Cl) and Bicarbonate (HCO3)

33
Q

What are two other, less common, extracellular electrolytes?

A

Urea and glucose

34
Q

Outline DNA replication, naming enzymes involved

A

1) Double helix unwinds - Topoisomerase.
2) Then unzips - Helicase.
3) Free nucleotides bind to complementary bases via Hydrogen bonds (A two bonds to T, C three bonds to G).
4) DNA Polymerase then creates covalent bonds.
5) Two new DNA molecules are created, each with one parent strand and one new strand

35
Q

What direction does DNA Polymerase read and synthesise DNA?

A

Read 3’ - 5’

Synthesised 5’ - 3’

36
Q

What is a primer?

A

Short strand of DNA which is the starting point for DNA synthesis, as DNA Polymerase can only add nucleotides to existing strands of DNA.

37
Q

What is an Okazaki fragment?

A

There is a leading and lagging strand during DNA replication. The lagging strand is synthesised discontinuously, making short fragments of double stranded DNA. These short fragments are Okazaki fragments.

38
Q

Outline transcription

A

1) DNA unwinds and unzips.
2) RNA polymerase creates a single strand of anti-parallel RNA (starts at promoter, ends at stop codon)
3) This forms a strand of pre-mRNA. Splicing occurs to remove introns (non-coding sections) and leave on extons (coding sections). This produces mature mRNA.
4) Many different combinations of exons means many different proteins can be formed.

39
Q

Outline translation

A

1) mRNA attaches to and is read by a ribosome in the cytoplasm.
2) Codons bind to complementary anticodons on tRNA molecules which carry amino acids.
3) The AAs join by peptide bonds to form a protein.

40
Q

What is a mis-sense mutation?

A

Point mutation where one nucleotide difference means a different codon and so amino acid is coded for.

41
Q

What is a non-sense mutation?

A

Point mutation which leads to the production of a stop codon, forming an incomplete protein.

42
Q

Outline the cell cycle

A

Mitosis (occupies small %)
G1 - Growth of cell, new organelles, proteins synthesised.
S - Synthesis, DNA is replicated and checked for mutations.
G2 - More cell growth, proteins for division are synthesised

43
Q

What is Mendel’s 2nd Law?

A

The Law of Independent Assortment - Alleles of one gene will sort into gametes independently of the alleles of another gene

44
Q

What is gonadal mosaicism?

A

When a person has 2+ populations of cells in their gonads and one is healthy while the other is genetically abnormal (i.e. any mutations)

45
Q

How does gonadal mosaicism arise?

A

When a mutation occurs in one cell of the developing embryo and goes on to become gametes, all containing the same mutation

46
Q

Describe autosomal dominant inheritance

A
  • Disease manifests in heterozygous state.
  • Males and females both affected.
  • Can be seen in multiple generations.
  • Can be transmitted between both sexes.
  • 50% chance of offspring being affected.
47
Q

Describe autosomal recessive inheritance

A
  • Disease manifests in homozygous state.
  • Usually only seen in 1 generation.
  • 25% chance off offspring being affected.
  • 50% chance of offspring being a carrier.
48
Q

Describe X-Linked inheritance

A
  • Disease caused by mutations in gene on X chromosome.
  • Usually only men affected and woman are carriers.
  • Cannot be passed from father to son (as father gives X chromosome to daughter.)
49
Q

Define lyonisation

A

When one copy of the X chromosome in females is inactivated during embryological development.

50
Q

What is Knudson’s 2-hit hypothesis?

A

The idea that non-inherited cancer requires 2 acquired mutations, whereas inherited cancer only requires one acquired mutation, as 1 is already inherited. Therefore more likely to develop an inherited cancer.

51
Q

Define penetrance

A

Proportion of carriers of a gene/set of genes showing the characteristic phenotype.

52
Q

Define variable expression

A

Variation in clinical features (type and severity) of a genetic disorder between individuals with the same gene alteration.

53
Q

Define sex limitation

A

Expression of a particular characteristic limited to one gender, even though both carry the gene for the characteristic e.g. BRCA gene in women.

54
Q

Define multifactorial disease

A

Disease due to a combination of environmental and genetic factors.

55
Q

When calculating risk of inheriting a disease from pedigrees, what calculation would you use?

A

Chance of parent 1 being a carrier (usually work out from pedigree) * Chance of parent 2 being a carrier (usually given prevelance in general population) * Risk to child if both parents are carriers

Phase 1 Med (20 decks)

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