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Medicine for the Engineer - Exam 1 > Cell > Flashcards

Cell Flashcards

1
Q

What’s the difference between pro- and eukaryotic cells?

A

Pro: Smaller one cell organism, missing mitochondria and nuclear membrane. Bacterias are pro.

Eu: Larger cells. Can be either uni- or multicellular. Tiny minority.

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2
Q

Metabolism consists of which two processes?

A

Catabolism and anabolism, where the former breaks up and the latter builds.

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3
Q

Which four categories can organelles be placed in?

A
  • Structure and communication
  • Anabolic
  • Catabolic
  • Energy
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4
Q

What are the five structural organelles?

A
  • Plasma membrane
  • Cytosol
  • Cytoskeleton
  • Centrosome
  • Membrane specialization, such as microvilli, cilia, and flagella
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5
Q

What are the six anabolic organelles?

A
  • Nucleus
  • Nucleolus
  • Ribosomes
  • Endoplasmic reticulum
  • Golgi complex
  • Vesicular transport, such as fagosome and endosome
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6
Q

What are the three catabolic organelles?

A
  • Peroxisome
  • Lysosome
  • Proteasome
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7
Q

What is the energy organelle?

A

Mitochondrion

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8
Q

What are the components of the plasma membrane?

A
  • Phospholopids
  • Proteins, integral and peripheral
  • Lipids, cholesterol and glycolipids
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9
Q

What are the functions of the plasma membrane? What is it permeable to?

A

Selective permeability. Permeable to water, nonpolar molecules (fatty acids, fat-soluble vitamins, steroids, oxygen, and CO2). Not permeable to ions and large uncharged polar molecules (glucose, amino acids)

Functions: Ion channels, transporters, receptors, enzyme, linker, and cell identity.

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10
Q

What are the transport alternatives across the plasma membrane?

A

Passive (no ATP)

  • Diffusion, simple and facilitated
  • Osmosis

Active (ATP)

  • Primary
  • Secondary
  • Vesicular
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11
Q

Another name for adrenaline?

A

Epinephrine

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12
Q

What is the structure of cytosol?

A
  • About 50% of cell volume
  • 75 to 90% water
  • Ions, glucose, amino acids, fatty acids, lipids, ATP, and waste products
  • Lipid droplets, glycogen granules
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13
Q

Which chemical reaction occurs in the cytosol?

A

Glycolysis, protein synthesis, degradation, and intermediary metabolism

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14
Q

What are the three types of cytoskeleton, what are their sizes, and what are they made of?

A

Microfilaments

  • Thin
  • Made of the protein Actin polymer

Intermediate filaments

  • Intermediate size
  • More than 50 different proteins, e.g. keratin

Microtubuli - Transport coordinated by Centrosome

  • Largest in size, long hollow tubes
  • Made of protein Tubulin polymer
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15
Q

What are the functions of the three types of cytoskeleton?

A

General functions: Cell shape, cell adhesion, movement, and keeping organelles in place.

Microfilaments

  • Forming microvilli : Increase surface area
  • Cell strength and shape : Cell adhesion
  • Movement: muscles, cell locomotion

Intermediate filaments

  • Actual skeleton structure, strength : keeps organells in place
  • Cell adhesion

Microtubuli

  • Cell shape
  • Cell functions : Movement of organelles
  • Form cilia, flagellae, centrosome : movement
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16
Q

What is the structure and function of the centrosome?

A

Location and structure

  • Located near nucleus
  • Consists of a pair of centrioles with 9 clusters of microtubule triplets each
  • Surrounded by pericentriolar area/material/matrix which are hundreds of proteins

Functions

  • Microtubuli organisation center
  • Mitotic spindle, in charge of the splitting of the nucleus during cell division
17
Q

What are the three specialized membrane structures, what are they made of, and what are their functions?

A

Microvilli

  • Actin (microfilaments)
  • Increase surface area : e.g. intestinal epithelia

Cilium

  • Microtubuli and basal bodies
  • Movement of fluids at a surface : e.g. mucous out of the lungs

Flagellum

  • Microtubuli and basal bodies
  • Movement of entire cell : In human cells only in sperms
18
Q

What is the structure and function of the nucleus?

A

Structure

  • Usually one per cell – but can be none or several (muscle, hepatocytes, osteoclasts)
  • Surrounded by a double membrane inner and outer nuclear, creates nuclear envelope
  • Outer membrane continuous with ER, which contains ribosomes
  • Nuclear pores, made up of 50-100 proteins
  • Chromosomes wound up around chromatin (complex of DNA and protein)

Function

  • Barrier! Separate biochemical compartment within the cell.
  • Organised
  • Contains and organise our genome
  • DNA and RNA synthesis
19
Q

What is the structure and function of the nucleolus?

A

Structure

  • Located inside the nucleus
  • No membrane
  • Chromosomal regions that contain the rRNA genes for ribosomes
  • Composition: DNA, RNA, and protein

Function

  • Site of rRNA transcription
  • Ribosome production factory
  • Active protein synthesis (liver cells) : large nucleoli
20
Q

What is transcription?

What is translation?

A

Transcript: Process of forming mRNA out of DNA

  • In the nucleus
  • DNA base triplets – corresponding RNA codon
  • Proteins involved – RNA polymerase
  • Promoter and terminator sequences determine where
  • tRNA, mRNA and rRNA

Translation: Process of building protein based on mRNA

  • In the cytosol
  • Caused by ribosomes (Proteins/rRNA), tRNA, aa
21
Q

What is the structure and function of the ribosome?

A

Structure

  • No membrane
  • A small “40S” and a large subunit “60S” (assemble in the cytosol to the ribosome “80S”)
  • Composition: rRNA, protein. During protein synthesis: also tRNA and mRNA
  • Free in the cytosol, attached to the ER or inside mitochondria

Function
- Site of protein synthesis

22
Q

What is the structure and function of the endoplasmic reticulum?

A

Structure

  • Large folded membrane structures. 50% of the membrane structures : 10% of the cell volume.
  • Continuous with the Nuclear Envelope
  • Two different portions
    1. Rough Endoplasmic Reticulum - RER (Covered with ribosomes)
    2. Smooth Endoplasmic Reticulum – SER (No ribosomes)

Function - Lipid and Protein synthesis and modification

RER:

  • Glycoprotein synthesis, processing and sorting : for the membrane (pm or organelles) or for secretion
  • Phospholipid synthesis

SER:

  • Synthesis of fatty acids and steroids (estrogen/testosterone)
  • Special functions in hepatocytes (liver cells): Smooth ER enzymes help release glucose into the bloodstream and detoxify a variety of drugs and potentially harmful substances, (alcohol, carcinogens).
  • Special functions in myocytes (muscle cells): Calcium ions in sarcoplasmic reticulum.
23
Q

What is the structure and function of the golgi complex?

A

Structure

  • 2 to 20 membrane sacs called cisterns
  • Cis-, medial- and trans- golgi
  • Vesicles

Function

  • First step after ER in a transport route for the membrane
  • Processing and sorting of proteins to plasma membrane, lysosomes or secretion
  • Modifcation results in Glycoproteins / Lipoproteins
  • Trans Golgi network, a distribution and sorting center
24
Q

What is the vesicular transport system, and what variations within this transport system is there?

A

Definition and variations

  • Vesicles are small round structures formed when budding off an existing membrane
  • Active transport, require ATP
  • Endocytosis. Transport into the cell. Bulk phase or receptor mediated endocytosis. Phagocytosis.
  • Exocytosis. Transport out of the cell.

Function

  • Transport of substances from one part of the cell to another
  • Exocytosis in secretory cells release enzymes, hormones, mucus
  • Exocytosis in nerve cells secrete nerurotransmittors
25
Q

What is the structure and function of the mitochondrion?

A

Structure

  • 100 to 1000 in a cell
  • Double membrane structure
  • A mitochondrial matrix enclosed by, Inner (Cristae) rough folded and outer smooth membrane.
  • Has some DNA, RNA, Ribosomes and synthesize a few proteins (37 genes : ribosomal RNA tRNA and mitochondrial component proteins.)

Function

  • Most of the cells ATP production
  • Citric acid cycle and Electron transport chain
26
Q

What is the structure and function of the peroxisome?

A

Structure

  • Small spherical membrane compounds (microbodies)
  • Contain dense areas of proteins (enzymes, oxidases)

Function

  • Performs oxidative/peroxidative reactions using oxygen and hydrogen peroxide
  • Divides into new peroxisomes
  • Synthesis of phospholipids like myelin
27
Q

What is the structure and function of the lysosome?

A

Structure

  • Lumen contain many different proteins: 60 digestive enzymes
  • Membane enclosed in relatively large vesicles
  • Membrane carrier proteins transport digested molecules into the cytosol

Function

  • Catalytic reactions, degrade many different molecules from endocytosed vesicle
  • Low pH in lumen (central cavity)
  • Autophagy, reusing the cells own structures
  • Autolysis, destroying the entire cell
28
Q

What is the structure and function of the proteasome?

A

Structure

  • Protein bodies made of proteases (No membrane)
  • In the cytosol and nucleus

Function

  • Selectively degrade unneeded, damaged or misfolded proteins in the cytosol
  • The protein “Ubiquitin” is used as a marker : polyubiquinated proteins
  • Some proteins has to be removed for control : transcription factors
29
Q

What are prions?

A

Prions are infectious proteins. Misfolded proteins with the ability to transmit their misfolded shape onto normal variants of the same protein. They characterize several fatal and transmissible neurodegenerative diseases.

  • Only difference is their folded three-dimensional structure. More β-sheets.
  • Protease resistant, which leads to accumulation. No refolding or degradation.
30
Q

What are the different pathogens?

A
  • Viruses (DNA/RNA in shell of proteins)
  • Bacteria (free living cells, more complex)
  • Fungi, Protozoa, Metazoa (Parasitic worms, Ascaris lumbricoides)
31
Q

What are the four different protein structures?

A

Primary, composition of amino acids.
Secondary, alpha helix and beta pleated sheet.
Tertiary, 3D shape of different secondary structures which form a specific subunit.
Quaternary, combination of different subunits.

32
Q

Definition of a gene

A
  • Genes are made up of fixed sequences of DNA, about 1000 make up a gene
  • The basic physical and functional unit of heredity
  • Act as instructors for Proteins (1,5%) and RNA
  • Few hundred DNA bases to more than 2 million bases
  • Estimated that humans have between 20,000 and 25,000 genes
  • Change in sequence of nitrogenous bases is called mutation
33
Q

How is the genome organised?

A
  • In the nucleus
  • 46 Chromosomes in 23 pairs
  • Chromatin, histones package the DNA
34
Q

What is the replication process?

A
  • Process where a double stranded DNA molecule is copied to produce two identical DNA molecules
  • Replication occur before cell division
  • DNA polymerase, RNA primers

Medicine for the Engineer - Exam 1 (6 decks)

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