3.Cell Structure Flashcards
What is microscopy
The study using microscopes to produce an enlarged image of an object
What’s the equation for magnification
Image
———————— = magnification
Actual
What is resolving power/resultion
The minimum distance apart that two objects can be in order to be seen as separate images
Depends on wavelength or form of radiation used
The greater the resolution the clearer and more precise the image is
What happens during cell fractionation
Isolation of organelles
1-tissue placed in cold buffered solution that has same water potential as tissue
2-homogenation-cells broken up in homogeniser, resultant fluid (homogenise) filtered to remove any unbroken cells
3-ultracentrifugation-homogenate places in centrifuge and spun at slower speeds to separate out the heaviest layers, from sediment and is removed, then spun again and refiltered until all layers of cell have been removed.
Facts about electron microscope
Short wavelength = high resolving power
Uses electrons so beam can be focused
Facts about a Transmission electron microscope (TEM)
Beam of electrons produced by electron gun are focused by a condenser electromagnet
Needs very thin specimen so electrons can pass through
Resolving power 0.1nm
Parts absorb electrons so appear dark on screen
Why is the solution, a tissue is placed in during cell fractionation, cold buffered and same water potential?
Cold-reduce enzyme action to prevent the break down of organelles
Buffered-so pH doesn’t fluctuate and alter structure if organelles
Same W.P-prevents bursting or shrinking of organelles
What are the limitations of the TEM
Living organisms can’t be studied as in vacuum
Not in colour even though goes through complex staining
Extremely thing specimen
Artefacts may be in image that are from specimen
Facts about the scanning electron microscope (SEM)
Beam electrons directed straight onto surface from a above
Beam passed back n forth in regular pattern
Electrons catered by contours of specimen
Computer processes a 3D image
Resolving power of 20nm
Limitations of SEM
In vacuum so no living organisms
Complex staining process
Artefacts distort what we see-can’t be sure it’s real
What is apart of the nucleus
Nuclear envelope-double membrane, continues with ER
Nuclear pores-allow passage of molecules out of nucleus
Nucleoplasm-granular jelly that makes up bulk of nucleus
Chromosomes-protein bound linear dna
Nucleolus-manufactures ribosomal dna and assembles ribosomes
What’s the function of a nucleus
Acts as control centre through productions of mRNA, tRNA and protein synthesus
Retains genetic material of DNA and chromosomes
Manufactures ribosomal dna
What makes up mitochondria
Double mebrane-controls exit and entry of material
Cristae-inner folded membrane, for attachment of proteins and enzymes
Matrix-contains proteins, lipids, ribosomes and dna that allows mitochondria to control production of own proteins
Whats the function of mitochondria
Site of aerobic respiration and responsible for production of ATP
What makes up a chloroplast
Envelope-double plasma membrane, highly selective enter and exit
Grana-stack to form thylakoids, contain chlorphyll, first stage of photosynthesis
Stroma-fluid filled matrix, second stage photosynthesis, contain starch grains
What’s the function of chloroplasts
Grana membranes proved large surface area for the attachment of chlorophyll, enzymes carry out photosynthesis
Fluid of stroma contains the enzymes needed to make sugars
Chloroplasts contain dna so they can quickly manufacture some of the proteins needed for photosynthesis
What are the two types of endoplasmic Reticulum
Smooth er
Rough er
What are the differences between smooth ER and rough ER
Smooth has ribosomes, large area for protein synthesis and glycoproteins, pathway fir transport of materials through cell
Rough no ribosomes, more tubular, synthesis and storage and transport of lipids and carbohydrates
What makes up the Golgi apparatus
Cisternae-flattened sacs that stack up
Vesicles-small rounded hollow structures
What are the functions of the Golgi apparatus
Modification or proteins-add carbs to form glucolipids
Labels them-sorted and sent to right place of cell
Transported in vesicles-move to membrane and fuse with it and release
Produce secretory enzymes-like those by pancreas
Secrete carbs-like those used in making cell walls
Transfer and modify and store lipids
Form lysosomes
Facts about lysosomes
Produced by Golgi
Contain enzymes eg lysozymes and lipas es
They Isolate enzymes until they are needed
Functions of lysosomes
Hydrolyse material ingested eg phagocyte
Release enzymes to outside of cell
Digest worn out organelles
Autolysis-complete break down of cells after they’ve died
What are the two types of ribosomes
80S-eukaryotes bigger
70S-prokaryotes found in mitochondria, chloroplasts smaller
What’s the function of ribosomes
Site of protein synthesis
What’s the structure of a cell wall
Plant cell walls structure is cellulose macrofibrils
Animal cell-large number of polysaccharides and has a middle lamella-thin layer marking boundary between adjacent walls and cements together
What’s the function of the cell wall
Provide mechanical strength to prevent cell bursting under the pressure created by osmosis of water
Gives mechanical strength to plants as a whole
Allows water to pass along it and contributes to movement of water though plant
What’s the cell wall of fungi made of
Chitin
What is a vacuole
Fluid filled sac bound by a single membrane (tonoplast)
Contains a solution of mineral salts sugars amino acids waste and pigment
What’s the function of a vacuole
Support herbaceous plants and herbaceous parts of woody plants by making them turgid
Sugars and amino acids act as temporary food store
Pigments colour petals to attract pollinating insects
Relate cell ultrastructre to function
Each organelle has own function
Cells with lots of mitochondria produce lots of ATP used as energy
These cells have high rate of metabolism
The denser and more numerous Curtiss the greater the metabolic rate of cell
What is cell specialisation
cells all initially have same functions
As mature they evolve and have fewer or more of certain organelles in order to be best adapted for function
What are the atwo types of tissue
Epithelial and xylem
What is a tissue
Group of cells with the same function that are grouped together for efficiency
Facts about epithelial tissue
Found in animals-sheets of cells that line surface of organs
Have protective or secretory functions
Two types -ciliated and epithelial
Epithelial-thin surface line organs where diffusion occurs
Ciliated-lines ducts such as trachea, used to move mucus over epithelial surface
What are organs
Where tissues aggregate into organs
Combo of tissues that are co ordinated to perform a variety of functions, often have on predominant major function
An example of an organ and its many tissues in animal
Stomach
Muscles churn food
Epithelium protect stomach wall produce secretions
Connective tissue hold together all tissues
Example of organ in plants
Leaf tissue Palisade mesophyll photosynthesis Sponges mesophyll adapter for gaseous exchange Phloem organic molecules away from leaf Xylem transport water and ions into leaf
What is an organ system
Group of organs working as a single unit
What organs are in the digestive system
Salivary glands, oesophagus, stomach, duedenum, ileum, pancreas and liver
What organs are in the circulatory system
Heart
Arteries
Veins
What organs are part of respiratory system
Trachea
Bronchi
Lungs
What are the main components of eukaryotic cells
Distinct nucleus Dna association with histones No plasmids Linear dna Membrane bound organelles Chloroplasts in plants Mitochondria 80S No capsule Cellulose cell wall
What are the main components of prokaryotic cells
No true nucleus Dna not associated with proteins Circular dna and plasmids No chloroplasts, chlorophyll associated in cell surface membrane No membrane bound organelles 70S Mucilaginous layer-capsule No mitochondria Cell wall of murein
What’s the structure of a bacterial cell
Cell wall of murein Mucilaginous capsule Cell surface membrane Cytoplasm 70S Glycogen and lipid droplets Circular dna and plasmids
Structure of viruses
Acellular Non living Nucleic acids enclosed in capsid Lipid envelope or capsid Attachment proteins to allow to attach to host cells and replication
What is phase on of mitosis
Interphase
Cell doesn’t divide
3 stages
G1-growth of cell, doubles size, contents duplicate, proteins synthesis
S-dna replication (semi conservative)
G2-cell continues to grow, checks for errors, prep for mitosis
Definition of mitosis
The nuclear division of. Parent cell to produce two genetically identical daughter cells
What happens in phase two of mitosis
Nuclear division
thas 4 stages -PMAT
What happens during prophase
1-chromosomes condense-shorter n thicker
2-nuclear envelope and nucleoli disintegrate
3-centrioles move to opposite poles of cell
4-mitotic spindle fibres form
What happens during metaphase
Chromosomes which are made up of two chromatids joined by centromere
1-chromosomes line up at metaphase plate at equator of cells
2-attach fo spindle fibres via centromere
What happens during anaphase
Spindle fibres contract
Sister chromatids pulled apart and pulled to opposite poles
What happens during telophase
Spindle fibres disintegrate
Nuclear envelope and nucleolus reform around chromosomes
Chromosomes diffuse
Cleavage furrow begins to form
What happens in phase 3 of mitosis
Cytokinesis
Cytoplasm splits and forms two daughter nuclei
How do viruses replicate
- Attach to host cell via attachment proteins and release their nucleic acids into host cells
- nucleic acid provides the instructions for host cells metabolic process to produce viral components, nucleic acids and structural proteins needed to assemble new viruses
What is cancer caused by
Growth disorder of cells due to damage to genes that control cell growth
Leads to uncontrolled growth and division of cells as a result a group of abnormal cells form TUMOUR
Why do most cells divide?
For growth and repair
What’s the difference between malignant tumours and benign tumours
Less compact and grow faster and cancerous
More compact grow slower non cancerous
How is cancer treated
Involves killing cellls by blocking part of cell cycle eg drugs that prevent dna replication or inhibit metaphase stage by interfering with mitotic spindle formations
What are the problems with the treatment of cancer
Disrupt normal cell cycles
Rapidly diving cells vulnerable to damage
