Cell Biol Flashcards
Who came up with cell theory?
Shleider Schwann
Who first grew isolated cells?
Harrison
How do cells divide?
They double
What are the core abilities of prokaryotic and eukaryotic cells?
Metabolism
Response to stimuli
Reproduction
Protein synthesis
Who came up with the central dogma theory?
Francis Crick
What is mycoplasma laboratorium?
A synthetic species of bacterium derived from a synthetic genome transplanted into a mycoplasma mycoides cell
What are the limitations of central dogma?
One gene (one enzyme) is too simplistic
What is redundancy?
Many genes play a small part in most functions
What is the nucleus surrounded by?
Double membrane, nuclear envelope and nuclear pores
What is the nucleus involved in?
Synthesis of mRNA, rRNA and tRNA
What type of structure does DNA have?
Double helix
What are the two pyrimidines?
Thymine and cytosine
What are the two purines?
Adenine and guanine
What is the nucleoplasm?
Proteins and DNA suspended in aqueous medium
What is the nucleolus involved?
Ribosome synthesis
What is nuclear lamina?
Forms a thin layer underlying and supporting the in nuclear membrane
What are components of the nucleolus?
Fibrillar centre
Dense fibrillar component
Granular component
What is the gene present of the Y chromosome in males?
SRY gene
What is the dense version of chromatin?
Hetarochromatin
What is the less dense version of chromatin?
Euchromatin
Where are many active genes found?
Euchromatin
What is a chromosome?
A single DNA molecule complexed with an equal mass of protein?
What is DNA bound to to form chromatin?
Histones
What are topoisomers?
Genetically identical but topologically different isomers
How many chromosomes are in a single diploid human cell?
46
What’s a typical size of a eukaryotic cell?
10-100 micrometers
What composes 70% of our cells?
Cytosol
What makes up the cytoskeleton?
Filamentous protein structues
What is a cytoskeletons function?
Establishing a cells shape
Determine intracellular location
Transport
Specialise functions
What are filaments held in?
Bundles/ networks by cross linking proteins
What else can the cytoskeleton be used for?
Generating cell polarity
What’s a typical example of a filament?
Actin
Functions of actin
Mechanical strength
Anchoring organelles
Helps cells divide in cytokinesis
What are microtubules?
Long straight hollow cylinders built by the assembly of dimers of alpha and beta tubuling
How does a positive end of microtubules grow?
By polymerising tubular dimers
What causes niemann-pick C disease?
Mutation in NPC1 or NPC2 genes
What are typical symptoms of niemann-pick C disease?
Dementia
Behaviour problems
Epilepsy
What are cilia and flagella constructed from?
Microtubules
What do secretory vesicles carry?
Cargo
How do secretory vesicles carry cargo?
Collect cargo in buds arising from membranes
What happens when vesicles membrane becomes part of plasma membrane?
The vesicles contents are lost out of the cell
What are the two types of secretory pathways?
Constitutive and regulated
Two types of endocytosis
Pinocytosis and phagocytosis
What do endosomes mature into?
Lysosomes
What is the internal pH of endosomes?
Acidic
What are lysosomes?
Membrane enclosed organelles containing over 50 degradation acid hydrolase enzymes?
What does endocytosis use to degrade materials?
Endosomes
What is autophagy?
Digestion of obsolete components of the cell
Give an example of neurodegenerative disorder?
NPC disease
Does the SER have ribosomes?
No
What is the SER involved in?
Calcium storage and lipid metabolism
What is the RER?
ER consisting of cisternae which have ribosomes on the outer surface?
What are proteins?
Amino acid joined by peptide bonds into long chains
What is the important pathway for protein maturation?
Sequence-> confirmation-> funciton
How is protein maturation achieved?
By forming bonds linking different regions of polypeptide chains e.g disulphide chains
What is methylation?
Attachment of methyl groups to amino acids
What is myristoylation?
Attachment of fatty acids to proteins
What is glycosilation?
Attachment of sugars to proteins
What is proteolytic cleavage?
Removal of sections of the polypeptide chains that are not required in the mature protein?
What causes cystic fibrosis?
Misfolding of the proteins CFTR
What is the Golgi apparatus?
A collection of flattened membrane bound cysternae and small spherical vescicles
What is bulk flow?
Smooth ER
Cis Golgi network
Cis Golgi stack
Medial Golgi stack
Trans Golgi stack
Trans Golgi network
What happens in the trans Golgi network?
Where stack break up into different transport vesicles that are dispatched to their final destinations
Wheee are phospholipids and fatty acids synthesised?
The ER
Where are glycolipids and sphyngomyelin synthesised?
Golgi
What makes up the phospholipid bilayer?
Hydrophilic head
2 hydrophobic tails
What’s cholesterol?
A major plasma membrane component?
What are non steroid hormone receptors?
Integral transmembrane proteins
What is solubilisation?
Disruption of lipid bilayer by detergents
What is the electrochemical gradient?
Combined force of a concentration gradient or charge gradient
What is symport?
Two substrates moved in the same direction
What is anti port?
Two substrates moving in different directions
What’s a glycolipid?
Consists of polysaccharide chains attached to lipids/proteins
Where a glycolipids located?
Extracellular surface of plasma membrane
What are lipid rafts?
Organising centres for membrane assembly, influencing membrane fluidity and membrane protein trafficking
Where is the glycoalyx located?
The cytosilic surface
What is the mitochondria?
Organelles that oxidise fuel molecules to generate ATP via oxidative phosphorylation
What are peroxisomes?
Enzyme containing organelles which produce hydrogen peroxide
What is the role of mitochondria in metabolism?
Oxidative decarboxylation and ETC
6 criteria of living organisms
Organised structures
Metabolism
Growth
React to stimuli
Reproduction
Evolve
3 domains of life
Archea
Eubacteria
Eukaryotes
What are archea?
Microbes that live in extreme environments
What is the cell cycle?
The stages that cells have to progress through in the mechanism of asexual reproduction.
What is the cell cycle made up of?
Mitosis and interphase
Types of cells
Singular and multitude
What is a singular cell?
Function and survive independently
What are multitude cells?
Cells that do not survive once separated
What is retinoblastoma?
Growth inhibitory TS protein
What is cell fate?
Divide
Differentiate
Die
What is mitosis comprised of?
Prophase
Pro metaphase
Metaphase
Anaphase
Telophase
What happens during interphase?
Cell increase in size
Generates 2 chromatids
Centrosome is duplicated
What is the centriole?
A hollow cylindrical, organelle
What happens during prophase?
Duplicated DNA condense to form 2 sister chromatic
DNA becomes visible to light microscope
Cenreikwa more to opposite ends of poles
Cycling and cyclin dependent kinases are activated
What happens during pro metaphase?
Complete dissolution of NM
Formation of spindle structure
Proteins attach to centromeres creating the kinetocjores
Kinetochores attach to the spindle microtubules and begin active movement
What happens during metaphase?
Microtubules form spindle pole body
Spindle fibres align chromosomes along equator
2 members of sister chromatid attach to a microtubules
What happens during anaphase?
Sister chromatids move outward
Separation results in the formation of two daughter chromosomes
Pulled apart and slowly move towards the spindle pole
Kinetochore tubules get shorter and spindle pole moves outwards
Results in chromosome separation
What happens during telophase?
Chromatids arrive at opposite ends of each pole
New M! Form around daughter nuclei through the action or phosphatases which remove the phosphate groups
Chromosomes begin to disperse
Spindle fibres begin to disperse
Beginning of cytokinesis
What is cytokenesis?
Cellular segregation
What happens during cytokenesis?
Cytoplasm divides into 2 by a contrile ring of Actin and myosin filaments
End of cell division generations two daughter cells
Who discovered mitosis?
Walther Fleming
What is tissue culture?
Method of studying the behaviour of a cell
Why do we use tissue culture?
Cheaper
Reliable
Reproducible
Ethically acceptable
What did we use before tissue culture?
Bacteria cell culture
Why don’t we use bacterial cell culture anymore?
They failed to be representative models of humans and higher mammals and their respective diseases
Three types of tissue culture
Organ culture
Primary explants
Cell culture
Advantages of organ culture
Retain cell- cell interactions
Differentiated
Disadvantage of organ culture
Heterogenous
Poor growth
Cannot be efficiently propagated
Poor sample reproducibility
Large amount of material requirements
High maintenance costs
What cell is adherent?
Epithelial
What cell is non-adherent?
Blood
What is the major purpose on senescence?
Evolutionary aspect in the cellular prevention of cancer
Common requirements of primary cell culture
Fat and necrotic tissue removes
Finely chopped tissue
Enzymes used for disaggregation should be removed
High cell concentrations are required
Preferably embryonic/ tumour tissue
How to determine cell concentration?
Counted using a haemocytometer and trypan blue
What does trypan blue do?
Indicates cell membrane permeability
What are quiescent cells?
Are in a reversible cell cycle arrest and able to respond to mitosis stimuli
What are optimum conditions for cell growth?
7.5 pH
37°c
Serum
Gas phase
Osmolality
Types of cell culture
Finite (normal)
Continuous (abnormal)
Advantages of using primary cell culture system
Differentiated into other cell types
Relevant to normal tissue
Provide for better models of investigation of disease
Disadvantages of using primary cell culture
Finite growth span
Extremely sensitive to surroundings
Expensive to maintain
Heterogenous
What happens to cells when they reach 100% confluency?
Undergo cellular stasis and are quiescent
How do cells interact with each other?
Cell junction proteins
What are the cell junction proteins?
Tight junctions
Adheren junctions
Desmosomes
Gap junctions
Focal adhesions
Hemidisomes
What are cellular signals for quiescence and how are these signals propagated in the cell?
Structural proteins which are integral to the cell-cell interaction
Components of extracellular matrix
Fibrous structural proteins
Water hydrated gels
Adhesive glycoproteins
What are the different stem cells?
Totipotent
Pluripotent
Multipotent
Why do stem cells continually divide?
Continusted presence of telomerase
What the cell separation techniques?
Adherence
Density
Antibody
What does adherence use?
Gravity
What does density use?
Centriguation of total blood cells
How to isolate stem cells
Using cellular surface protein markers?
What does antibody use?
Fluorescent and magnetic
What is a nucleoside?
Base and deoxyribose
What is a nucleotide?
Nucleoside and phosphate
What is a nucleid acid?
Polymer of nucleotides
What is a pyrimidine?
A nitrogen containing a 6 member end single ring compound
Cytosine and thymine/uracil
What is a purine?
A nitrogen containing a 9 member end single ring compound
Adenine and guanine
How are nucleotides joined?
Phosphodiester bonds
What does the 5’ end contain?
Free polar phosphate group
What does the 3’ end contain?
A free polar hydroxyl group OH
What is the sense strand?
5’-3’
What is the anti sense strand?
3’-5’
What are oligonicleotides?
Short nucleic acid chains
What are polynucleotides?
Much longer chains
Where is mRNA found?
Nucleus
Where is rRNA found?
Cytoplasm
Where is tRNA found?
Cytoplasm
What is semi conservative replication?
Each daughter DNA duplex contains 1 strand from parent molecule and one newly synthesised DNA strand
What is semi-discontinuous replication?
Only one leading strand is synthesised continuously
What is semi-discontinuous replication?
Only one DNA strand is continued
What is transcription?
Begins when an enzyme call RNA polymerase attaches to the template DNA strand and begins to catalyse the production of complementary RNA
What are polymerases?
Large enzymes composed of a dozen subunits and when active on DNA they are usually complexed with other factors
What are the 3 types of RNA polymerase?
RNA pol I
RNA pol II
RNA pol III
What does RNA pol I do?
Transcribes the genes that encode most of the rRNAs
What does RNA pol II do?
Transcribes the messenger RNA
What does RNA pol III do?
Transcribes the genes for one small rRNA
What is transcription?
Process by which DNA is copied to mRNA by RNA molecules
What is splicing?
Removal of intron sequences
What are stop codons?
TAA, TAG & TGA
What is the start codon?
ATG
What do all protein sequences begin with?
Methionine
How is PCR used in medicine?
Carrier testing for genetic diseases
And prenatal diagnosis
What are the types of artificial cloning?
DNA/gene cloning
Reproductive cloning
Therapeutic cloning
What is DNA/gene cloning?
The transfer of a DNA fragment of interest from one organism to a self replicating genetic element such as a bacterial plasmid
What is reproductive cloning?
A technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal
What is therapeutic cloning?
Creating a cloned embryo to produce embryonic stem cells with the same DNA as the donor cell
What is pharmacogenetics?
The study of how genes affect a persons response to drugs
What are genes?
Units of hereditary that contain information that determine specific traits
What are alleles?
Variations of the same gene
What is the inheritance pattern of alleles controlled by?
Meiosis
What is meiosis?
The process of cell division during gamete formation
What is independent assortment?
The segregation of alleles of one gene is independent of the segregation of the alleles of another gene
What is a dihybrid cross?
Mating between two strains differing in two characteristics
What are the two main functions of meiosis?
Produces recombinant chromosomes or a mixture of genetic information from both parental chromosomes
Halves the number of chromosomes in a cell
What is a rare example of genetic linkage in humans?
Nail-Patella syndrome and ABO blood groups
When will recombination frequency be low?
If two genes are very close
When will recombination frequency be high?
If two genes are very far apart
What are autosomal recessive diseases?
PKU, sickle cell anaemia, albinism and CF
What are autosomal dominant diseases?
Huntingtons disease, colour blindness and haemophiliacs
What are X linked recessive disorders?
Colour blindness and haemophilia
What are X linked dominant disorders?
Hypophosphotemia
Frequency of an allele question
Number of copies of the allele/ number of copies of all alleles at the locus
What is the Hardy-Weinberg equation?
P^2+2pq+q^2=1
What is a genotype?
The inherited alleles of an individual
What is a phenotype?
The physical characteristics of an individual
What are two types of variation in human chromosomes?
Changes in chromosome structure
Changes in the number of chromosomes in a cell
When does duplication occur?
When a chromosome segment is duplicated by mistake during chromosomal replication prior to cell division
When does deletions occur?
When a fragment of chromosome is missing and can cause severe abnormal traits
What is inversions?
When sequence of genes on a chromosome is reversed
What is translocations?
Movement of a chromosomal segment from one chromosome to another
What are diseases associated with translocations?
Leukaemia and Down’s syndrome
What is polyploidy?
Three or more sets of the same chromosomes
What is aneuploidu?
An increase or decrease of the number of individual chromosomes
Examples of aneuploidy:
Nullisomy
Monosomy
Trisomy
Tetrasomy
How does aneuploidy occur?
Caused by two homologous chromosomes not separating during meiosis
What causes Down’s syndrome?
Extra copy of chromosome 21
What is Jacob’s syndrome expressed as?
XYY
What is Klinefelters syndrome expressed as?
XXY
What is Trisomy X expressed as?
XXX
What is Turner’s syndrome expressed as?
XO
What causes Edwards syndrome?
An extra copy of chromosome 18
Does cell division result in daughter cells during meiosis?
No
