Pack 2 - Cells Flashcards
What is cell theory?
- The cell is the most basic unit of life
- All living organisms are composed of one or more cells
3, All cells arise from pre-existing, living cells
Define Eukaryote
An organism whose: -cells contain a true nucleus (surrounded by the nuclear membrane)
- cells contain other membrane-bound organelles
- genetic material (DNA) is contained within the nucleus and is organised in chromosomes
List 13 Parts of a Eukaryotic animal cell
Mitochondrion Ribosome RER SER Plasma membrane Cytoplasm Lysosome Golgi apparatus Nucleus: -Nucleolus -Chromatin -Nuclear pore -Nuclear envelope
Define intrinsic
Running through the membrane
Extrinsic
Outside the membrane
List 7 parts of a Eukaryotic plant cell that aren’t in an animal cell
Filamentous cytoskeleton Cell wall Chloroplast -Thylakoid membrane -Starch grain Vacuole - Tonoplast
How would you describe the RER to the nuclear envelope?
Contiguous
Define cisternae
Hole inside a cavity
List 6 parts of a nucleus
Nuclear envelope -RER -Cisternae Nuclear pores Chromatin Nucleolus
What are the functions of a nuclear envelope?
Control entry and exit of substances
Contain reactions inside the nucleus
What is the function of nuclear pores?
Allow passage of large molecules out of the nucleus (eg. mRNA)
What is the function of the nucleolus?
Manufactures rRNA
Assembles Ribosomes
Define protein bound
DNA wound around proteins called histones
What are ribosomes made of?
Large subunit
Small subunit
How are proteins synthesised in the ribosomes?
tRNA carrying amino acids - depends on which the mRNA calls for
mRNA carries the genetic information - each of which codes for a particular amino acid
rRNA associates with a set of proteins to form ribosomes
Multiple amino acids are strung together, creating proteins
Describe a prokaryotic ribosome
70S - around 20nm in diameter
Describe a eukaryotic ribosome
80s - around 25nm in diameter
What is the function of ribosomes?
Site of protein synthesis
What is the function of RER?
Pathway for transport of materials, especially proteins through the cell
What is the function of SER
Synthesises, stores and transports lipids
Synthesises, stores and stransports carbohydrates
How is the RER adapted to be particularly effective at protein synthesis
Large surfave area to volue ratio
Name 2 parts to the Golgi apparatus
Vesicles
Cisternae
Give 5 functions of the Golgi apparatus
Adds carbohydrates to proteins to form glycoproteins
Produces secretory enzymes (eg in the pancreas)
Secretes carbohydrates (eg those used in plant cell walls)
Modifies/processes triglycerides
Combines triglycerides with proteins
Forms lysosomes
What is a Golgi vesicle?
A small, rounded, hollow structure
That transports substances to and from the Golgi apparatus.
Some of these are lysosomes.
What is the difference between a Golgi vesicle and a lysosome?
A lysosome is a vesicle that stays inside the cell.
How to vesicles leave and join organelles?
Pinch off
Fuse
Give 4 functions of lysosomes
Hydrolyse material engulfed by phagocytic cells
Release enzymes to the outside of the cell to destroy material around the cell (exocytosis)
Digest worn out organelles so that chemicals may be re-used
Completely break down cells after they have died (autolysis)
Give the approximate size of a lysosome
Up to 1μm in diameter
Define exocytosis
The release of enzymes to the outside of the cell to destroy material around the cell
Define autolysis
Completely breaking down cells after they have died
List 4 parts of a mitochondrion
Outer membrane
Inner membrane
Intermembrane space
Cristae
State 3 things about mitochondria
Rod shaped, 1-10μm in length
Site of aerobic respiration
Produce ATP
Why do mitochondria sometimes appear to be round in microscope images?
They look round when cut transversely
How is energy released from glucose?
Mitochondria are the site of aerobic respiration
Mitochondria require glucose in the manufacture of metabolic energy (or ATP)
What type of cell would have many mitochondria?
A metabolically active cell eg muscle (Contraction) or epithelial (Active Transport)
Why do tissues that perform active transport require a lot of mitochondria?
Mitochondria are the site of aerobic respiration
Respiration produces ATP
ATP is needed for active transport
Why might someone with mitochondrial disease find exercise difficult?
Mitochondria are the site of aerobic respiration
Respiration produces ATP/releases energy
Energy/ATP is needed for muscle contraction
What does the energy do from respiration that results in ATP
ADP + P -> ATP
Name 12 parts of a chloroplast
Ribosome Plastoglobule Internal membrane Intermembrane space External membrane Granum Chloroplast DNA Stroma Lamella Lumen Thylakoid membrane Thylakoid
How long is a chloroplast?
2-10μm in length
What is the function of a chloroplast?
Site of photosynthesis
How is a chloroplast adapted to its function?
Grana - large surface area to volume ratio for attachment of:
- chlorophyll
- electron carriers
- enzymes
(for 1st stage of photosynthesis).
Stroma - contains enzymes
(for 2nd stage of photosynthesis).
DNA and ribosomes - for quick protein synthesis for photosynthesis
Where are chloroplasts found?
Plants and algae
Name 2 parts of a vacuole
Vacuole
Tonoplast
Give 3 functions of a vacuole
Supports herbaceous plants by making cells turgid
Temporary food store (sugars and amino acids)
Pigments may colour petals to attract pollinating insects
Name 7 parts of a plant cell wall
Middle Lamella Primary cell wall Plasma membrane Pectin Cellulose microfibril Hemicellulose Soluble protein
Give 3 functions of a plant cell wall
Provides mechanical strength to recent cells bursting due to reassure built up at water moves in by osmosis
Mechanical strength to the plant as a whole
Allows water to move along it, contributing to water movement through the plant
What does the cell wall consist of in fungi (eukaryote)?
Chitin
Glycan
Glycoproteins
What does the cell wall consist of in algae (eukaryote)?
Cellulose and/or
Glycoproteins
Define homogenised
The same all the way through (the mixture)
Define sediment
The contents of the bottom of a test tube after ultracentrifugation
Define supernatant
The contents at the top of a test tube after ultracentrifugation
Define ultracentrifugation
Spinning at a very high speed
10 mins 1,000G
10 mins 3,500G
10 mins 16,500G
What would sediment 1 likely contain?
Nuclei
What would sediment 2 likely contain?
Mitochondria
What would sediment 3 likely contain?
Lysosomes
What is left after sediment 3?
Ribosomes
What is cell specialisation/differentiation?
The process by which a cell becomes specialised to perform a specific function
Why do all cells in an organism contain the same genes?
They are all produced by mitosis from one fertilised egg
Define tissue
A collection of similar cells that perform a specific function
Define organ
An organ is a combination of tissues that perform one major function
Define organ system
A number of organs working together
Define squamous (epithelial tissues)
Flattened like a pancake
Define cuboidal (epithelial tissues)
In a cube shape
Define columnar (epithelial tissues)
In a column shape
Define stratified (epithelial tissues)
Arranged like bricks
Define pseudostratified columnar (epithelial tissues)
Looks stratified but is actually columnar
They are simply thicker at one end than the other
Why are there 3 different types of stomach muscle?
To churn in all directions increasing digestion rate
Name the 11 parts of the digestive system
Salivary glands Pharynx Mouth Oesophagus Liver Stomach Gall bladder Pancreas Small intestine Large intestine Anus
Name the 2 main parts of the circulatory system
Heart Blood vessels (containing blood)
Name the 5 parts of the respiratory system
Mouth and nose Trachea Bronchus Lung Diaphragm
What is there a lack of in prokaryotic cells?
Compartmentalisation
In what form is the genetic material in a prokaryotic cell?
A single molecule of “circular” DNA
What 9 things make up a bacteria cell (prokaryotic)?
Capsule Cell wall Plasma membrane Cytoplasm Ribosomes Plasmid Pili Bacterial flagellum Nucleoid (circular DNA)
What are the 2 functions of a bacteria cell wall (prokaryotic)?
Physical barrier (excludes some substances)
Protects against mechanical damage and osmotic lysis
What is the function of a bacterial cell surface membrane (prokaryotic)?
Differentially permeable layer; controls entry and exit of chemicals
What is the function of the circular strand of DNA in bacterial cells (prokaryotic)?
Carries genetic information for replication of bacterial cells
What is the function of the bacterial plasmid (prokaryote)?
Contains genes that aid survival (eg. antibiotic resistance)
What are the 2 functions of a bacteria cell’s capsule (prokaryotic)?
Protects form other cells
Helps bacteria stick together for protection
What is the function of bacterial flagellum (prokaryote)?
Locomotion
What 7 things make up the HIV virus?
Docking glycoprotein Transmembrane glycoprotein Lipid envelope Matrix Reverse transcriptase RNA Capsid
What is the function of reverse transcriptase?
Copies the viral RNA back into DNA once inside the host cell
Why are viruses described as particles rather than cells?
Viruses can only multiply/replicate inside living host cells and so are technically not living
What is the formula triangle that links magnification, image size and object size (and units)?
D
A M u
What do you do if there is a tricky image to measure but a scale bar is provided?
Measure the scale bar
Define resolution
The shortest distance between two points that can still be distinguished by the observer
Define magnification
How large the microscope can make the image appear to be
What is the approximate resolution of the human eye?
0.2mm
What is the approximate resolution of the light microscope?
0.2μm
What is the approximate resolution of the best electron microscope?
0.1nm
What are the 8 parts to a light microscope?
Eyepiece lens Revolving nose piece Objective lenses Coarse focus Fine focus Specimen stage Condenser lens and diaphragm Light source
Describe the passage of light through a light microscope
Human eye
Eyepiece lenses
(Intermediate image)
Objective lenses
Object (specimen and slide)
Condenser lens
Light source
Name two requirements for light microscopy specimens
Thin - for light to pass through and to only focus on one ‘layer’ of the cell
Selectively stained - as thin sections are often transparent and so cannot be seen normally
What is an eyepiece graticule?
A disc that fits into the eyepiece lens of a light microscope
What is a stage micrometer?
A glass microscope slide that is placed on the specimen stage of a light microscope
How long does a stage micrometer scale measure?
1mm
How many notches is a stage micrometer divided up into?
100
How long is one notch on a stage micrometer?
10μm
How do you calibrate an eyepiece graticule?
1) Insert and line up the stage micrometer
2) Find where they converge
3) Divide by number of units on eyepiece graticule scale
How do you measure using an eyepiece graticule?
Simply multiply the value of one eyepiece unit by however many eyepiece units there are
Describe the passage of electrons through a TEM
Electron source
Magnetic condenser
Object
Magnetic objective
Intermediate image
Magnetic projector
Fluorescent screen
Describe the passage of electrons through an SEM
Electron source
Anode
Condenser lens
Scan coils
Objective lens
Secondary electron detector
Sample
Define artefact (in light microscopy)
A structural detail caused by the preparation of a specimen and is thus not a legitimate feature of the specimen
Give an example of an artefact in light microscopy
Air bubbles
Give examples of electron microscope artefacts
Dust
Cracks in the specimen
Too thick a coating
Charging artefacts - Lines and black halos caused by electrons spilling up caused charges
Which microscope can see living tissue?
Light
Which electron microscope can see in 2D and which in 3D?
TEM - 2D
SEM - 3D
What is the maximum magnification of a light microscope?
×1,500
What is the maximum magnification of a transmission electron microscope?
×10,000,000
What is the maximum magnification of a scanning electron microscope?
×500,000
Which microscope can sometimes see in genuine colour?
Light microscope
