Cells Flashcards
What microscope has a higher resolution and magnification?
Electron microscopes
What microscope gives a colour image?
Light microscope
What microscope is lighter and cheaper?
Light
What microscope is more expensive?
Electron microscope
What resolving power and magnification do TEM and SEM have and what one has the highest resolving power?
Both have high resolution and magnification TEM has higher resolving power
What condition must the cell be in to use a TEM or SEM? What process is complex?
Must be vacuum can’t be living and must be extremely thin and complex staining process
What one out of TEM and SEM produce colour images?
SEM
What may the images contain when using a TEM or SEM?
May contain artefacts
What one out if SEM and TEM produce a 3D image?
SEM
What is the formula of magnification?
Magnification = size of image\ size of object
What is the definition of resolution?
The minimum distance apart that two objects can be in order for them to appear as separate items?
What is cell fractionation?
The process where cells are broken up and the different they contain are separated out
What are the 3 conditions the tissue must be place in by cell fractionation?
Cold, buffered and same water potential
Why must the cell be placed in a cold solution?
To reduce enzyme activity that may break down the organelles
Why must the cells be placed in buffered solution?
So ph doesn’t change which could alter the structure of the organelles or affect the function of the organelles
Why must the cells be place in a solution which is the same water potential/ isotonic?
To stop osmosis to prevent organelles bursting or shrinking due to osmotic gain or loss of water
What are the two stages of cell fractionation?
Homogenisation and ultracentrifugation
What is homogenisation?
Cells are broken up by a homogeniser which breaks down the cell wall and membrane releasing the organelles from the cell to produce a fluid called homogenate which is filtered to remove cells and large pieces of debris
What is ultracentrifugation?
Process where the fragments in the filtered homogenate are separated in a machine by a centrifuge it spins the tubes of homogenate at a high speed to create a centrifugal force
What are the 3 steps of ultracentrifugation?
- Spun at slow speeds to remove heaviest organelles
- Fluid at top called supernatant removed and transferred to another tube and spun again at a faster speed
- Next heaviest organelle taken out then spun until all the organelles are separated
What is calibration of a microscope?
Where you line up the stage micrometer and eye piece graticule so you can find the difference in magnification by seeing how many eye piece graticule fit inside the stage micrometer to work out the magnification
What is the nucleus function?
Contains hereditary material and controls cells activities
What is the nuclear membrane?
Double membrane which is continuous with the ER and it controls the entry and exit if materials ad contains the reactions in the nucleus
What do nuclear pores do?
Allow passage of large molecules
What is the nucleoplasm?
Granular jelly like material that makes up most of the nucleus
What are chromosomes ?
Consist of linear hound dna by proteins
What is the nucleolus?
Small spherical region in nucleoplasm produces RNA and assembles ribosomes
What are the 3 functions of the nucleus?
- Control centre of cell produces RNA and tRNA and protein synthesis
- Retains genetic material in the form of DNA and chromosomes
- Manufacture ribosomal RNA and ribosomes
What shape and size are mitochondria?
Rod shaped 1-10 micrometers
What is the function of the double membrane around the mitochondria?
Controls entry and exit of materials
What is the cristae in a mitochondria?
Inner of two membranes is folded to form extensions providing a larger sa for attachment of enzymes and proteins for respiration
What is the matrix in the mitochondria?
Make sup most of it contains proteins, lipids, ribosomes and DNA allows them to control production of their own proteins
What is the function of mitochondria?
Sites of aerobic respiration production of ATP required for active transport
What is the general shape of chloroplast?
Disc shaped 2-10 micrometres long 1 micrometer diameter
What does the chloroplast envelope do?
Double plasma membrane selective of what comes in and out of the chloroplast
What is grana in a chloroplast?
Stacks of disc like structures called thylakoids contain green pigment called chlorophyll so it is where light absorption takes place
What is stroma in chloroplasts?
Fluid filled matrix where synthesis of sugars occur 2nd stage of photosynthesis also contain starch grains
What is the main function of chloroplasts?
Harvest sunlight to carry out photosynthesis
What is the endoplasmic reticulum?
An elaborate 3D systems of sheet like membranes spreading through cytoplasm continuous with outer nuclear membrane encloses a network of tubules and flattened sacs called cisternae
What is rough endoplasmic reticulum?
Has ribosomes on outer surface
What are the functions of RER?
Provides larger SA for synthesis of proteins and glycoproteins provided pathway for transport of materials
What is smooth endoplasmic reticulum?
Lacks ribosomes on surface so more tubular
What is the function of SER?
Synthesise, store and transport lipids and carbohydrates so cells with lots of lipids, carbohydrates and proteins have a larger ER
What is the golgi apparatus?
A compact set of flattened sacs cisternae with small hollow vesicles
What does the golgi apparatus do?
Modifies proteins by adding non protein components and labels and sorts out where they have to go and also form lysosomes
In a Golgi apparatus how are modified proteins transported?
In golgi vesicles pinched off golgi cisternae
What are lysosomes?
Isolate lysozyme which is an enzyme that hydrolyses the cell walls of certain bacteria then release them to outside of cells or into cells phagocytic vessel
What are the functions of lysosomes?
- Hydrolyse materials ingested by phagocytic cells
- Release enzymes to outside of the cell to destroy material outside the cells
- Break down the cells after they have died
What cells are lysosomes abundant in?
Secretory cells
What are ribosomes and where are they found?
Small cytoplasmic granules found in cytoplasm or on RER
What are the two types of ribosomes?
80s - found in eukaryotic cells around 25nm
70s - found in prokaryotic cells smaller than 80s
What are ribosomes made up of?
1 large and 1 small subunit containing RNA and proteins
What is the function of ribosomes?
Site of protein synthesis
What is the cell wall and where is it found?
Microfibrils and cellulose embedded in a matrix making it very strong. Found in all plant cells
What is the middle lamella in a cell wall?
A thin layer which is the boundary between adjacent cell walls which cements cells together
What are the 3 functions of cell walls?
- Provide mechanical strength prevents cell from bursting
- Provide mechanical strength to plant
- Allows water to pass through the plant
What are cell walls in algae mad up of?
Cellulose or glycoproteins
What are cell walls of fungi made up of?
Chitin
What are vacuoles?
Fluid Filled sac bounded by a single membrane called the tonoplast
What do plant to vacuoles contain?
A Solution of minerals salts sugars amino acid’s wastes and pigments
What are the three functions of vacuoles?
- Plants and the cell to be turgid
- Sugars and amino acid’s may act as a temporary food store
- Pigments may colour petals to attract pollinating insects
How are cells specialised?
Different genes are expressed and turned on or off
What is the order of organisation?
Cells, tissues, organ, organ system
What Is the definition of tissues and what are two examples?
A group of similar cells that work together to carry out a particular function for example epithelial tissue xylem tissue and phloem tissue
What is an organ and what are two examples?
Combination of tissues coordinated to perform a variety of functions for example organs used for digestion and a leaf
What is an organ system and what are two examples?
Organs work together as a single unit to perform a specific function efficiently. For example the digestive system and the respiratory system
What Is the difference between eukaryotic and prokaryotic cells?
Prokaryotic crlls are larger and have nucleus bounded by nuclear membranes whereas prokaryotic cells are smaller and have no nucleus
What are five parts of a bacterial cell?
Large circular strand of DNA, cell-surface membrane, capsule, cell wall, plasmid, ribosomes, flagellum and cytoplasm
What Is a virus?
A small acellular nonliving particle
How do you viruses multiply?
They can only multiply in host cells
Why are viruses surrounded by a lipid envelope or capsid that has attachment proteins?
To identify and attach to a host cell
What are six parts of a virus?
Attachment protein, capsid, lipid envelope, matrix, reverse transcriptase enzyme, genetic material RNA
What does mitosis do?
Produces 2 daughter cells with the same number of chromosomes as the parent cells
What happens in interphase?
DNA replicates and becomes a chromosome when the two chromatids are attached by a centromere
What happens in prophase?
- Chromosomes become visible and shorten and thicken
- Spindle fibres develop from each centriole
- Nucleolus disappears and nuclear envelope breaks down
- Chromosomes drawn towards equator
What happens in metaphase?
- Chromosomes now seen as 2 chromatids
2. Microtubules from poles attached to centromere pulled to arrange themselves on equator
What happens in anaphase?
- Centromeres divide in two chromatids pulled apart
2. Chromatids move to opposite poles now called chromosomes
What happens in telophase?
- Chromosomes reach poles become long and thin then disappear fully to form chromatin
- Spindle fibres disintegrate nuclear envelope and nucleolus reform
What happens in cytokinesis?
Cytoplasm divides
What are the 4 main stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase
How do prokaryotic cells replicate?
Binary fission
What is cancer?
Group of diseases caused by the damage to genes that regulate mitosis and the cell cycle leading to uncontrolled growth and division of cells causing a tumour to develop
What type of tumour is cancerous?
Malignant
Is the treatment for cancer and why is it used?
Disrupt the cell cycle by preventing DNA from replicating inhibiting metaphase by interfering with spindle formation
What Is the problem with chemotherapy?
Upsell cycle of normal cells leading to hair loss
