Module 2.1 Cell Structure Flashcards
Magnification🔎
How much bigger an image appears compared with the original object
Resolution
The ability to be able to distinguish between 2 points that are very close together
Advantages of light microscopes🔬
Relatively cheap, easy to use, portable, can study living specimens
Max magnification of a light microscope 🔬
1500 times
Max resolution of a light 🔬
200nm
How do you calculate total magnification
Magnifying power of the objective lens TIMES BY magnifying power of the eyepiece lens
Disadvantages of electron microscopes
Large, expensive, needs a great deal of skill and training to use, specimens need to be dead
Image formed by transmission electron microscopes
2D Black and White image
Image formed by scanning electron microscope
3D Black and White (although false colour can be added)
Acetic oncein binds to DNA and stains chromosomes
Dark red🌶👹👺💃🏿🎒🦀🍎🍒🍷
Name an example of an all purpose stain
Methylene blue 💤🐟💦👖👕🐳🐬☄️🎽🚙🛢
How would you prepare a specimen?
Dehydrate the specimen, embed it in wax (to prevent distortion) and section the specimen
Calculations involving magnification formula
Magnification = Image DIVIDED BY Actual size
Features of a generalised animal cell
Ribosomes Mitochondria Nucleolus Nucleus Smooth Endoplasmic Reticulum Plasma membrane Golgi apparatus Lysosomes Nuclear envelope Rough Endoplasmic Reticulum
Features of a generalised plant cell 🌱
Chloroplast Amyloplast containing starch Golgi apparatus Smooth Endoplasmic Reticulum Ribosomes Nucleolus Nucleus Nuclear envelope Rough Endoplasmic Reticulum Plasma membrane Cell wall Vacuole Mitochondria
🌟Describe the stages in the production of extracellular proteins
- mRNA copy of the gene is made in the nucleus 〰 (transcription)
- mRNA leaves the nucleus through a nuclear pore
- mRNA attaches to a ribosome (e.g. attached to the rough endoplasmic reticulum). The ribosome reads the instructions to assemble a protein (translation)
- Molecules are “pinched off” in vesicles and travel towards the Golgi apparatus
- Vesicle fuses with the Golgi apparatus
- Golgi apparatus processes and packages 📦 the molecules ready for release
- Packaged molecules 📦are “pinched off” in vesicles from Golgi apparatus and move towards the plasma membrane
- Vesicle fuses with the plasma membrane
- Protein released out of the cell by exocytosis
Light microscopes can be used to observe dead specimens? True or false
False
Light microscopes can be used to observe tissue in colour? True or false
True
Light microscopes can be used to observe organelles of cells? True or false
True
Light microscopes can be used to observe the movement of cells? True or false
True
What features of a 🌱 cell would you expect to be able to see under a light microscope?
The cell wall, the nucleus, the cytoplasm and the chloroplasts
Explain why you can only see limited organelle when looking at a 🌱cell under a light microscope
The resolution of a light microscope is 200nm and the max magnification is 1500 times. The magnification and resolution are too low to observe most organelle of the cell.
Scanning electron microscopes can be used to observe 2D images, true or false?
False
Scanning electron microscopes can be used to observe cell surfaces, true or false?
True
Scanning electron microscopes can be used to observe cells in colour, true or false?
False
Scanning electron microscopes can be used to observe cells in real time, true or false?
False
Strengths and weaknesses of light and electron microscopes
Light microscopes strengths:
Cheap, portable, easy to use, can study living or dead specimens with them
Light microscopes weaknesses:
Limited resolution and magnification, most organelles are too small to see at this power
Electron microscopes strengths:
High magnification and resolution
Electron microscopes weaknesses:
Large, needs skills and training to operate, specimen must be dead
Which of these statements are true?
1) Stains can be used to distinguish between different cell types
2) Stains can be used to fix specimens
3) Stains can be used to distinguish different tissue types
4) Stains can be used to highlight particular organelle
1, 3 and 4 only
How would you prepare a temporary mount of a specimen for a light microscope?
Section the specimen, put it on a slide, stain it, put a coverslip over the specimen
How would you calculate magnification?
Image size divided by actual size
How would you calculate the image size?
Actual size times by magnification
How would you calculate the actual size of a cell?
Image size divided by magnification
Organelle present in animal cells
Nucleolus Nucleus RER SER Ribosomes Mitochondria Golgi apparatus Centrioles Plasma membrane Cytoskeleton
Organelles present in plant cells🌱
Nucleus Nucleolus RER SER Ribosomes Mitochondria Chloroplasts Golgi apparatus Cellulose cell wall Plasma membrane Large central vacuole Cytoskeleton
Prokaryotic cells don’t have a nucleus, true or false?
True
Prokaryotic cells have many organelles, true or false?
False
Prokaryotic cells have a cellulose cell wall, true or false?
False
Prokaryotic cells have ribosomes, true or false?
True
Describe the differences in function between the RER, SER and Golgi apparatus
RER is coated with ribosomes that synthesise proteins
SER synthesises lipids
Golgi apparatus helps 📦 and modify proteins for exocytosis
Proteins cross the plasma membrane by what process?
Exocytosis
Why do the beta cells in the pancreas (beta cells produce insulin, a protein) have lots of RER?
RER coated with lots of ribosomes
Ribosomes synthesise proteins
Beta cells of the pancreas produce insulin, a protein
Suggest why beta cells in the pancreas need large amounts of ATP
Proteins are secreted from the beta cells by exocytosis which requires ATP/is an active process
Which are true?
1) The cytoskeleton is made of microtubules
2) The cytoskeleton is involved with the production of protein
3) Flagella and cilia are made of microfilaments
4) Microtubule proteins transport vesicles along microtubules
ONLY 1 and 4
Role of flagella
Movement of the cell
Role of cilia
Movement of the cell
Movement of substances e.g. Mucus
Role of microtubules
To maintain the shape of the cell
Role of microtubule motors
Movement of vesicles along microtubules
How is the cytoskeleton involved in movement inside and outside of the cell?
Microtubule motors move vesicles along microtubules inside the cell
Flagella/cilia are made from microtubules on the surface of the cell which helps the cell to move
The lengthening and shortening of microtubules inside the cell helps the cell to move
Cytoskeleton
Network of protein fibres within the cell that give the cell structure and shape
🌟Microtubules
Hollow cylinders of tubulin
25nm diameter
Maintain cell shape
Anchors organelles
In flagella and cilia, the structure is a cylinder of 9 microtubules in a circle and 2 more microtubules in a central bundle
Can help move microbes
How chromosomes are moved during mitosis (spindle fibres)
How vesicles move from the ER to Golgi using microtubule motors (requires ATP)
Flagella and cilia
Sticks out of the surface of the cell
Each one is a cylinder with 9 microtubules in a circle and 2 more in a central bundle
Can move using ATP
Cilia
Large no. of them on ciliated epithelial cells
Moves egg down Fallopian tube
Beat to move mucus
🌟Intermediate filaments
10nm Thick cables of keratin Maintains cell shape Anchors nucleus Anchors organelles
🌟Actin microfilaments
2 intertwined strands of actin 7nm diameter Maintains cell shape Causes muscle contractions Involved in cytokinesis Allows pseudopodia seen by amoeba and some WBCs
Vesicles
Membrane bound sacs
Carry substances
Features of prokaryotic cells
Mesosomes - inner folding, large SA for respiration
Ribosomes - synthesise proteins (smaller than in eukaryotes)
Plasmid - genetic material
Pilli - for conjugation
Slime capsule - keeps cell moist
Chromosomal DNA - contains instructions to make proteins
Cell wall - made of murein/peptidoglycan
Nucleus
Surrounded by nuclear envelope Nuclear pores allow mRNA and nucleotides through Contains genetic material (chromatin) Contains nucleolus Controls cell
Mitochondria
2 membranes separated by inter-membrane space
Inner membrane folded = cristae
Aerobic respiration takes place in mitochondria to release ATP
RER
System of cisternae
Ribosomes line it
Involved w/ protein synthesis and transport
SER
System of cisternae
Lacks ribosomes
Involved w/ synthesis and transport of lipids
Ribosomes
Involved w/ protein synthesis Move along mRNA Read nucleotide code to synthesise proteins Ribosomes are made of rRNA + protein 1 large + 1 small subunit
Golgi apparatus
More compact that SER
Made of flattened membrane sacs
Modifies and packages 📦 proteins
Forms lysosomes
Lysosomes
Membrane sac
Contains digestive enzymes
Destroys worn out parts of cell
Cytoplasm
Aqueous
Contains simple ions, amino acids, ATP, sugars, fat droplets
Cell membrane
Boundary between cell + environment Fluid mosaic model Phospholipid bilayer Proteins Cholesterol Glycolipids Glycoproteins
Centrioles
ONLY in animal cells
Migrate to poles of cell during mitosis and produce microtubules (spindles) to pull chromosomes apart
Chloroplasts
PLANTS ONLY Stroma Thylakoids Grana Intergranal lamellae Chlorophyll Site of photosynthesis
Starch granules
PLANTS ONLY
temporary stores of carbohydrates
Cell wall
Made of cellulose
Provides strength
Allows water to move through the plant
Plasmodesmata
PLANTS ONLY
gaps that allow neighbouring cells to link
Continuation of cytoplasm
Average diameter of prokaryotic cell
0.5-5 micrometers
Average length eukaryotic cells
20-40 micrometers
Ribosome diameter in prokaryotes
18nm
Ribosome diameter in eukaryotes
22nm
A structure associated with the cytoskeleton that can help cells move
Flagellum Cilia Microtubules Microfilament Undulipodium
2 processes inside the cell that rely on cytoskeleton for movement
Chromosomes moving
Cytokinesis
Movement of organelles
RNA in protein synthesis
What events happen following production of extracellular proteins until they are released?
Protein pinched off by Vesicle Moves to Golgi apparatus Golgi processes and packages Moves in Vesicle to plasma membrane Exocytosis
What structure secretes mucus?
Golgi Vesicle
Why do ciliated cells have lots of mitochondria?
They need a lot of energy to waft mucus
V active
Vacuoles
Large, permanent organelle in plants
Tonoplast filled w/water and sugars to keep the cell turgid
🌟Stages of exocytosis
Vesicle moves towards cell surface membrane along microtubules
Vesicle fuses with the cell surface membrane
Protein released out of the cell by exocytosis
Movement of vesicles on microtubules and fusion of vesicles with the membrane requires ATP
🌟Stages of endocytosis
Molecule binds w receptor
Cell surface membrane invaginates (requires ATP)
Membrane fuses w itself to form a vesicle
Vesicle moves through cytoplasm to destination organelle
🌟Roles of the cytoskeleton
Cell support + stability to maintain cell shape
Movement of cilia
Movement of flagellum to move cell
Changing cell shape e.g. endocytosis and exocytosis
Moving organelles around inside a cell
Anchoring organelles
Moving chromosomes and mRNA
