Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

S1: Histo Final > Cytology > Flashcards

Cytology Flashcards

1
Q

Name 2 functions of membranes in a eukaryotic cell.

Provide pertinent nomenclature.

A
  1. Form a barrier between cell and external environment
  2. Subdivide the cell into the compartments (organelles) that are then able to maintain novel interior environments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 3 basic components of a membrane?

How are membranes visualized?

A
  1. Lipids
  2. Proteins
  3. Carbohydrates

Membranes cannot be visualized with light microscopy but can be visualized with electron microscopy (7nm thin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe a key characteristic of membrane lipids with regards to affinity for water?

How does this affect how membrane lipids interact with one another, and what do they form because of this?

A

Membrane lipids are amphipathic with uncharged, hydrophobic tails; and charged, hydrophilic heads.

This causes the formation of a lipid bilayer. Hydrophilic heads facing out, and hydrophobic tails facing in. This forms a hydrophobic center where membrane proteins can anchor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the fluid mosaic model.

For what molecules is the membrane permeable?

What molecules will require transport proteins because they will not pass freely.

A

The fluid mosaic model is the interpretation of the molecular organization of membranes to include a hydrophilic outer layer and hydrophobic center where proteins can anchor.

Permeable: small, uncharged

Inpermeable: large, ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What categories can we group membrane proteins into?

A
  1. Structure

Integral (ex: transmembrane proteins) - hydrophobic region embedded into hydrophobic core

Peripheral - not embedded, attach to either integral proteins or hydrophilic heads

  1. Function

Transport proteins (channel proteins, carrier proteins, pumps)

Receptors

Structural or anchoring proteins - attach cell to surroundings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the difference between the three types of transport proteins.

A
  1. Channel proteins - form pores for passive diffusion (ion-selective)
  2. Carrier proteins - drag molecules through membrane by hiding in cleft
  3. Pumps - use ATP to actively pump ions through the membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe how carbohydrates are involved in cell membranes.

What do they attach to? What does this form?

How does this appear on an electron microscope and what is the name for this coating?

A

Carbohydrates, mostly oligosaccharides, attach to extracellular domains of proteins and lipids to form glycoproteins and glycolipids respectively.

The large number of these carbohydrates attached to the outer surface looks like a “fuzzy coating” on electron microscopy. This outer “fuzzy” coating is called the glycocalyx.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the functions of particles and inclusions.

What are the two main types?

A

Particles and inclusions are used for synthesis and storage.

  1. ribosomes
  2. Glycogen particles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the structure and function of ribosomes.

Where do ribosomes exist in eukaryotic cells? What work is done at each of these locations?

Describe a polysome.

A

Ribosomes consist of a small subunit and large subunit made of ribosomal RNA and specialized proteins. They work to catalyze protein synthesis by bringing mRNA and tRNA together.

  1. Free ribosomes - most cellular proteins synthesized here, including 80% mitochondrial proteins
  2. Mitochondrial ribosomes - hand 20% of mitochondrial proteins
  3. Ribosomes bound to rough endoplasmic reticulum - proteins for Golgi apparatus, lysosomes, secretory granules, and plasma membrane

A polysome is a string of ribosomes connected to a single mRNA molecule - this occurs during protein synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe glycogen particles.

A

Storage form of polysaccarides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the general morphological characteristics of endoplasmic reticulum.

What are the morphological differences between smooth ER and rough ER?

Where would you be more likely to find prominent smooth ER versus rough ER?

A

General endoplasmic reticulum is made of anastomoses tubules and cisternae (flattened, pancake-like vesicles).

Smooth ER

  • no ribosomes
  • more tubular in appearance
  • more prominent in steroid secreting cells and liver cells
  • present in muscle tissues as the sarcoplasmic reticulum

Rough ER

  • ribosomes, rough appearance: more ribosomes on cytoplasmic side
  • mostly cisternae
  • more prominent is protein secreting cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the functions of smooth endoplasmic reticulum.

Describe the functions of rough endoplasmic reticulum.

A

Smooth endoplasmic reticulum

  • lipid and steroid metabolism: membrane synthesis and recycling
  • detoxification: contains enzymes that can detoxify carcinogens, pesticides, etc…
  • glycogen metabolism
  • contraction in muscle cells: storage and transport of Ca+ as sarcoplasmic reticulum

Rough endoplasmic reticulum

  • synthesis of proteins destined for export
  • synthesis of proteins for Golgi apparatus, lysosomes, and plasma membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the structure of the Golgi apparatus including the polarization.

Describe the two basic functions of the Golgi apparatus.

A

Series of stacked, flattened, membrane-limited cisternae and tubular extensions.

Cis golgi is the side receiving proteins from the RER.

Medial golgi consists of the middle cisternae.

Trans golgi is the cisternae from which mature proteins are transported.

Functions

  1. Posttranslational modification of proteins
  2. Sorting and packaging of proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the functions of the Golgi apparatus in detail including locations.

What are the three destinations of proteins leaving the golgi?

A

1. Modifications of proteins.

  • adding and removing sugar residues, sulfate, or phosphate groups
  • early stages in cis golgi, intermediate steps in medial golgi, and final modifications in trans golgi

2. Sorting and packaging proteins into transport vesicles: proteins bear specific signal sequences which direct them to 1 of 3 destinations

  • Secretory vesicles: stored proteins and other products in secretory vesicles undergo maturation, mature secretory vesicles then fuse with plasma membrane to release into extracellular space
  • Lysosomes: involved in digesting material taken up from outside and degradation of senescent organelles
  • Constitutive pathway: proteins in trans golgi not going to secretory vesicles or lysosomes are sorted into small vesicles and transported directly to plasma membrane to fuse with membrane (integral membrane proteins and proteins secreted into extracellular space)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the structure, function, and characteristics of lysosomes.

What is the sorting signal that directs proteins from the Golgi to lysosomes?

When this sorting signal pathway is disrupted what disease does this cause?

A

Spherically organelles of variable size produced by golgi

Digest material from outside and degradation of senescent organelles.

Expect low pH and presence of hydrolytic enzymes.

Mannose-6-phosphate is the sorting signal. When this mutates lysosomal proteins are secreted into the intercellular space resulting in I-cell disease (mucolipidosis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the three stages of lysosomes.

A
  1. Primary lysosomes: not yet received substrates
  2. Secondary lysosomes: fusion of primary with target
  3. Lipofuscin granules (residual bodies): senescent lysosomes with undigestible materials
17
Q

Describe structure and function of peroxisomes. What would you expect to find in a peroxisome?

A

Small, membrane bound organelle

Oxidizes large range of organic substances including very long chain fatty acids, and conversion of ethanol to acetaldehyde. Also breaks down hydrogen peroxide

Containes oxidative enzymes, specifically catalase

18
Q

Describe Zellweger syndrome and Adrenoleukodystropy.

Which organelle when dysfunctional causes these disorders?

A

Peroxisomes

1. Zellweger syndrome

  • mutation of proteins responsible for proper transport of peroxisomal enzymes from cytoplasm (synthesized on free ribosomes) to the peroxisomes
  • peroxisomes lack necessary enzymes
  • improper formation of myelin sheath, affects brain development
  • death before 6 months of age

2. Adrenoleukodystrophy

  • disruption of oxidation of very long chain fatty acids
  • accumulation of lipid in brain and adrenals
  • brain damage, failure of adrenal glands, and death
  • inherited X linked disorder
19
Q

Describe the structure and function of mitochondria.

A

Can change location and shape but all have an outer and inner mitochondrial membrane with an intermembrane space and mitochondrial matrix.

Outer mitochondrial membrane: contacts cytoplasm and intermembrane space, contains pores (anion channels) that allows passage of small molecules, ions, and metabolites

Inner mitochondrial membrane: highly folded into cristae, project into matrix, contains many enzymes involved in energy production

Intermembrane space: pH and ionic composition similar to cytoplasm but contains proteins unique for ATP production, Cytochrome C lives here

Mitochondrial matrix: enclosed within inner mitochondrial membrane; contains soluble enzymes for Kreb’s, DNA transcription, etc; contains mitochondrial DNA, mitochondrial ribosomes, rRNA, mRNA, and tRNA; contains electron-dense granules that store Ca++ for regulation of ions in cytoplasm

Production of ATP through oxidation of Peru ate and fatty acids

20
Q

Describe 3 differences between mitochondria and other organelles that support the hypothesis that mitochondria evolved from symbiotic prokaryotes.

A
  1. Mitochondria have own separate genome
  2. Mitochondria possess two membranes
  3. Mitochondria increase number by division
21
Q

Describe how mitochondrial disease typically present.

Where are mitochondrial proteins encoded?

Mutation in what kind of DNA can result in mitochondrial myopathies? What inheritance does this show?

A

Proximal muscle weakness, sometimes involve extra ocular muscles. Sometimes with neuro symptoms, lactic acidosis, and cardiomyopathy

About 1/5 of oxidative phosphorylation proteins are encoded buy mitochondrial DNA, rest is nuclear genome.

Mutations in mitochondrial and nuclear genome therefore can result in mitochondrial disease. However, mitochondrial DNA is strictly maternal inheritance.

22
Q

Describe the structure, function, and contents of the nucleus.

A

Large, membrane-limited organelle. Surrounded by double membrane called nuclear envelope.

Contains genome as DNA bound to proteins, this is known as chromatin.

Contains machinery for DNA replication, RNA transcription, and one or more nucleoli.

23
Q

Describe the structure of the nuclear envelope.

A

1. Outer nuclear membrane: continuous with RER, ribosomes commonly attached to cytoplasmic surface

2. Perinuclear space: continuous with lumen of RER

3. Inner nuclear membrane: able to bind chromatin and lamins, supported by rigid network of intermediate filaments

4. Nuclear lamina: thin, protein-dense, attached to inner nuclear membrane, represents skeleton of nucleus formed by lamins.

Lamins: intermediate filament proteins that disassemble during mitosis and reassemble after, cross-linked into orthogonal lattice attached to inner nuclear membrane

5. Nuclear Pores: openings in envelope that allow communication between cytoplasm and nucleus, protein “spokes” project into lumen, allow free passage of small particles

24
Q

Describe chromatin.

What are the two types of chromatin in a non-dividing cell?

A

DNA associated with nuclear proteins, like histones

  1. Euchromatin: transcriptionally active, loosely packed, light staining
  2. Heterochromatin: contains inactive DNA, densely packed, stains more intensely
25
Q

Describe the function and structures of the nucleolus.

A

Nucleolus is a small area where ribosomal RNA is processed and assembled into ribosomal subunits

  1. Fibrillar centers: contains DNA loops with rRNA genes and transcription factors
  2. Dense fibrillar component (pars fibrosis): contains ribosomal genes being translated and large amounts of RNA
  3. Granular component (pars granulosa): site of ribosome assembly with clusters of pre-ribosomal particles
26
Q

Describe the function of the cytoskeleton.

What are the 3 major types of filaments? What are their basic roles?

A

Determines shape, provides structural support, and plays role in motility.

1. Actin filaments (thin filaments): cell movement, shape, and organelle transport

2. Microtubules (thicker): organelle and vesicle movement, formation of mitotic spindle and chromosome movement, beating of cilia and flagella.

3. Intermediate filaments (intermediate): strong, flexible polymers that provide mechanical support by spreading tensile forces, maintain cell shape, and act as cocoon when cell is damaged; also anchor ion channel proteins

27
Q

What are the two forms of actin?

Describe the function of actin.

A

G-actin: soluble, monomeric, globular protein, can polymerize into double-stranded helical filament

F-actin: the double stranded helical filament formed by polymerized G-actin, occurs head-to-tail which gives polarity

  1. Can form cortex which is a thin sheath beneath the sytoplasm formed of cross-lined actin filaments
    - resists cell deformation, transmits forces, reinforces cell membrane
  2. Interacts with myosin to generate force and movement
28
Q

Describe the structure of microtubules.

Is there polarity?

A

Made of two globular proteins, alpha-tubulin and beta-tubulin that are polymerized into cylindrical polymers that are stiff and non-branching.

Tubules polymerizes side-to-side and head-to-tail, so there is a plus end (grows faster, in cell periphery) and a minus end (associated with microtubule organizing center or centriole).

29
Q

Describe the motor proteins associated with the various filaments of the cytoskeleton.

Are there any filaments that are not associated with motor proteins?

A

Actin (thin) filaments: associated with myosin to generate force and movement

Microtubules: associated with dynein (move to minus end/center, beating of cilia and flagella) and kinesins (more to plus end/periphery)

Intermediate filaments: not associated with motor proteins

30
Q

Describe the higher-order structures that microtubules are involved in.

A
  1. cilia and flagella: core is formed by axoneme, dynein arms attached to alpha tubule interacts with neighboring beta-tubule and walking along causes bending of axoneme

axoneme: formed by 9 doublets and a central pair of microtubules

  1. C_entriole (basal body)_: formed of 9 triplets of microtubules without a central pair, located at base of each ilium of flagellum
  2. Microtubule-organizing center (MTOC): found in all cells except neurons and RBCs, consists of two centrioles
31
Q

Describe the 6 classes of intermediate filaments and their distributions.

A
  1. Lamins: found in nucleus forming inner mesh work on inner side of nuclear envelope
  2. Keratins: found in epithelial cells
  3. Vimentin: found in fibroblasts of connective tissue
  4. Desmin: found in muscle cells
  5. Glial fibrillar acidic protein: found in glial cells, support cells of nervous system
  6. Neurofilaments: found in neurons
32
Q

What is the most commonly used combination of dyes when staining tissues?

How do cell components stain with this?

A

H&E dye: hematoxylin and eosin

hematoxylin: basic dye, stains acids
eosin: acidic dye, stains basic components

Stains pink: cytoplasm, mitochondria, collagen

Stains blue: RER, ribosomes, glucosaminoglycans, nucleus (dark blue/purple)

Does not stain: membranes, Golgi, SER

S1: Histo Final (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions