Cytology Flashcards
What does unicellular mean
Consisting of only one cell
What does multi cellular mean
Consisting of many cells
What Is know as the ultra structure
The fine structure of the cell as seen with the electron microscope
What is the basis of the cell theory of biology
1665- Robert Hooke looks at a cork under a microscope. Calls the chambers he sees “cells”.
1665- 75 Anton van Leeuwenhoek, the inventer of the microscope, studies organisms living in pond water. He calls them “animalcules”.
1830- German scientists Schleinden and Schawann summarise the findings of many scientists and conclude that all living organisms are made of cells. This forms the basis of the cell theory of biology
Why did Robert Hooke call cells cells
The little boxes reminded him of the rooms they stayed in at the monastery so he called them cells
What is the cell theory of biology
- all organisms are composed of cells
- the cell is the structural unit of life - units smaller than cells are not alive
- cells arise by division of pre-existed cells - spontaneous generation does not exist
- cells can be cultured to produce more cells
What is in vitro
Outside an organism or cell
What is in vivo
Inside an organism or cell
What is contained in a general animal cell
Golgi apparatus (dictyosome) Lysosome Vesicle Mitochondrion Cell membrane Cytoplasm Microvillus Centrioles Nucleus (nuclear membrane, nucleolus, chromatin-network) Ribosome Granular endoplasmic reticulum
What is contained in a general plant cell
Nucleus (chromatin-network, nuclear membrane, nucleolus) Vesicle Golgi apparatus (dictyosome) Mitochondrion Leucoplast Ribosomes Cytoplasm Chloroplast Tonoplast Large vacuole with cellsap Cell membrane Cell wall Endoplasmic reticulum
What parts is a cell broken down into
Cell - cell wall (non- living)
- protoplasm (living)
Protoplasm- cell nucleus
- cytoplasm
Cytoplasm- plasma lemma
- hyaloplasm
- membranous organelles
What is the protoplasm
The living part of the cell, it includes the nucleus, cytoplasm and plasmalemma
Where does the term protoplasm come from
From the Greek words proto (first) and plasma (formed)
What 6 chemicals is the protoplasm made up of
- water
- dissolved mineral salts
- lipids
- proteins
- carbohydrates
- nucleic acids
Where are cell walls found
All plant cells (cellulose), fungi (chitin), and bacteria (peptidoglycan).
What is the function of the cell wall
It helps protect the cell from mechanical injury and supports and strengthens the cell. As we cannot digest the cell walls, it forms roughage in our diets and helps to keep the colon functioning and clean
Provide Labels for the diagram representing the cell walls of four neighbouring cells
Cell 1, Cell 2, Cell 3, Cell 4, cell wall, plasmalemma/cell membrane, intercellular air space, middle lamella, cytoplasm.
What is the middle lamella made up of
Pectins
What is another word for cell membrane
Plasmalemma
How is a cell membrane formed
From a phospholipid bilayer with cholesterol molecules. Floating amongst the phospholipid and cholesterol molecules are many globular protein molecules.
Label diagram of the floating mosaic model
Exterior of cell,glycoprotein, double layer of phospholipids, canal protein, interior of cell, cholesterol
Why are membranes considered partially or selectively permeable
Proteins are grouped together and act as pores or transporters,allowing substances to pass through from one side of the membrane to the other. This means that membranes can control which substances may entrer or leave the cell and which not and it varies from cell to cell
What is the function of the cell membrane
It provides protection for the cell, it also transports substances in and out of the cell. Proteins in the membrane also act as receptors receiving and responding to messages
What is the structure of a nucleus
The nucleus is bounded by a double membrane, which allows the DNA to be isolated from the rest of the cell, decreasing the likelihood that it will be damaged.
What does the nucleolus look like and what does it do
It is a dense dark body. It is not enclosed by a membrane. It is a responsible for producing RNA and ribosomes.
Draw Label a nucleus diagram
NE- nuclear envelope S- perinuclear space N- nucleolus P- nuclear pore ER- endoplasmic reticulum E- euchromatin H- heterochromatin
What are nuclear pores and what do they do
They are spaces between the nuclear envelope that allow exchange of substances between the nucleus and the cytoplasm
How do chromosomes form
During the process of nuclear division, the chromatin becomes progressively more condensed until it takes on the form of slender threads called chromosomes. (In short chromosomes are super coiled up strands of chromatin)
What is the function of the nucleus
- Different proteins control the entire cell, and the nucleus organises which types of proteins are produced by the cell and when these proteins will be produced. The nucleus therefore controls the cell.
- The nucleus stores genetic information on the chromosomes and passes information onto the daughter cells when the cell divides
What is the cytoskeleton
A network of protein filaments placed in the cytoplasm required for cells to change their shape, move organelles and move from place to place
What are the two most important protein filaments
Actin filaments and microtubules
What is actin responsible for
For contraction (like in muscles)
What are the microtubules responsible for
For structural strength
What are the functions of the cytoskeleton
- to maintain the shape of the cell
- anchors the organelles in specific areas
- let’s substances move in the cytoplasm
- can change the shape of the cell when necessary
What are chromosomes made up of
DNA coiled around protein molecules called histones.
What are plastids
Plastids are relatively large organelles that are found only in plant cells.
What is the structure of a plastic
They are all surrounded by a double membrane (envelope), contain their own globular DNA and are thus able to replicate themselves and have ribosomes of the 70S size.
What are the three main types of plastids
Chloroplasts
Leucoplasts
Chromoplasts
What are proplastids
Small, colourless organelles that the three main plastids develop from
Where are chloroplasts located
They are located in the cytoplasmic ground substance in certain tissues of plants.
What are chloroplasts
They contain green pigments chlorophyll a and b, which trap light energy for photosynthesis
What are carotenoids
Pigments that are yellow and red
What is the space between the membranes where chloroplasts are bounded called
The intermembrane space
What is the stroma
The large central space enclosed by the inner membrane.
What is the stroma responsible for
It contains enzymes and is responsible for producing glucose from carbon dioxide and water using trapped energy from the sun.
What is the structure of thylakoids
A system of membranes which form a set of flattened, interconnected, disk like sacs
Where does the light phase of photosynthesis take place
In the chlorophyll electron carriers embedded in thylakoid membranes
What is a grana
A stack of thylakoids
What is the intergranal lamellae for
Links grana together
What organisms contain chloroplasts
All organisms form the plant and Protista kingdoms that use the sun for photosynthesis
Label and draw a diagram if a chloroplast
Starch grain Double membrane Stroma Ribosomes Globular DNA Granum Oil droplet Intergranal lamelae Thylakoid/lamelae
What is the balanced equation for photosynthesis
6CO2 + 6H2O —radiant energy—>
C6H12O6+ 6O2
What are leucoplasts
Colourless plastids found in the storage organs of plants.
What are the three main types of leucoplasts
Amyloplasts, proteoplasts, elaioplasts
What do amyloplasts store
Starch
What do proteoplasts store
Proteins
What do elaioplasts store
Oils
What plants are amyloplasts found in
Wheat, mealies, rice, potato etc
What plants are proteoplasts found in
Beans, peas, nuts etc
Where plants are elaioplasts found in
Sunflowers, seeds, olives, avocado etc
What May happen if leucoplasts are exposed to light
They may develop into chloroplasts
What are chromoplasts
They give petals, fruits and roots their yellow, orange and red colours
Where are chromoplasts found
I’m the cytoplasmic matrix of cells in the coloured part of certain plants
What are the colours of chromoplasts due to
Due to the presence of many carotenoid pigments within the stroma of the plastid
What is The function of chromoplasts in flowers
To attract pollinators, so they can be pollinated to form seeds
What is The function of chromoplasts in fruit
To attract animals to distribute their seeds when the are ready to be distributed
What are mitochondria
Fairly large organelles found in all cells except bacteria
Are mitochondria visible under compound light microscopes
Only if they are stained with a chemical which colours them specifically
The ultra structure of a mitochondria is only visible under a _______ microscope
Electron
How many membranes do mitochondria have
Two membranes separated by an inter-membrane space/ outer chamber
What is the structure of a mitochondrion
The outer membrane is relatively smooth, while the inner membrane is folded to form projections called Cristae.
What does the cristae do
It increases the surface area of the inner membrane. The cristae possesses “lollipop” particles projecting out into the inner chamber. It is here that energy is produces and stored in the form of ATP
What is the matrix
The space between the cristae
What does the matrix contain
Ribosomes of 70S size and DNA which are used to make some of the mitochondrion’s own proteins and enables it to replicate
Draw and label the diagram of a mitochondrion
Matrix, ribosomes, globular DNA, oil droplet, cristae, outer membrane, inner membrane, elementary processes
What is the balanced equation for respiration
C6H12O6 + 6O2 —> 6CO2 + 6H2O
ATP energy is released that is used to maintain life, for movement and heat.
What is the function of the mitochondria
The gradual release of energy from food in the presence of oxygen. The energy is temporarily stored in the carrier ATP (adenosine triphosphate)
What is the endoplasmic reticulum
It is a network of membranes running though the cytoplasm of every eukaryotic cell.
What is the structure of the ER (endoplasmic reticulum)
The membrane are continuous and consists flattened, membrane bound sacs called the cristernae
What is the ET lumen
The internal space of the sac
What is rough endoplasmic reticulum
When the endoplasmic reticulum is covered with ribosomes on their cytoplasmic sides
What is smooth endoplasmic reticulum
If no ribosomes are found on the surface of the ER. The smooth endoplasmic reticulum is more tubular in contrast to the flattened rough endoplasmic reticulum
What is the functions of the rough endoplasmic reticulum
To transport the proteins made by the ribosomes on their surface. At the edge of the ER small vesicles (sacks or vacuoles) break off and carry these proteins where it can be secreted from the cell and passed on to other organelles in the same cell.
What is the main function of the smooth endoplasmic reticulum
The synthesis of lipids
What are the different names for Golgi apparatus
Golgi complex, Golgi body, and dictyosomes
What is the structure of the Golgi body
Numerous flat, curved membrane bound sacs, called cristernae with several smaller vesicles entering and leaving it. These sacs are not interconnected and are never covered with ribosomes.each set forms a structure that looks like a pile of plates
What is a dictyosome
A stack of membranous sacs. Each dictyosome May contain 6-30 sacs (cristernae)
What is the bottom/outer face of a dictyosome called
The forming face (Cis). This face is usually convex and the sacs making it up are not as dilated.
What is the top of a dictyosome called
The top concave top or maturing face (Trans). The sacs making it up are dilated more.
What is the function of the Golgi apparatus
To transport and chemically modify the materials inside it. These materials eventually become secretary products.
How does the Golgi body transport and chemically modify materials
Vesicles containing newly synthesised proteins break off from the endoplasmic reticulum and travel towards the Golgi body where they fuse with the convex face. In the cristernae the proteins are chemically modified “finished off” before being exported from the cell. When the protein is ready, small vesicles break away from the concave face of the Golgi body and move towards the surface of the cell. They fuse with the plasmalemma and release their content to the outside. Not all protein product made by the Golgi body are secreted (some become lysosomes)
Where are lysosomes found
In most eukaryotic cells
What are lysosomes
They are small membrane bound vesicles that contain digestive enzymes in solution.
How are lysosomes formed
Are formed as buds which break away form the Golgi body.
What is the function of lysosomes
They help with intercellular digestion (eg when a white blood cell wants to destroy the bacteria that is engulfed)
What are polyribosomes/polysomes
Free ribosomes that occur in clusters
What is the function of ribosomes
To provide a platform on which protein synthesis takes place, where amino acids are joined together one by one to form polypeptide chains
What are centrioles
Small, hollow cylinders that occur in pairs in all animal cells and some lower plants like algae, but never higher plants
Where are centrioles found
In the cytoplasm near the nucleus in a region called the centrosome
What does a centriole contain
Each centriole contains nine triplets of microtubules, thus 27 microtubules
What is the function of the centrioles
To control the spindle fibre during cellular division
What are examples of vacuoles found in animal cells
Phagosomes, lysosomes and contractile vacuoles
What are vacuoles like in plant cells
Large, permanent and positioned fairly central in the cell
What are phagosomes
Food vacuoles
What are contractile vacuoles
These are found in unicellular organisms and play a role in the excretion of excess water. They contract rhythmically in order to move to the cells surface to release the water
How much volume can a plant vacuole occupy
Up to 90 % of the volume of the cell
What is the tonoplast
The membrane surrounding the vacuole
What are the functions of vacuoles
Turgidly and support, storage and excretion and digestion
How does a vacuole provide turgidity and support
Water enters the vacuole by osmosis. As a result pressure build up within the cell and the cytoplasm is pushed against the cell wall, keeping the whole cell firm, this is called turgidity.
What is turgor pressure
The pressure the cell contents exert on the cell wall
What is it called when a plant cell has been maximally filled with water
It is said to be turgid
What is it called when a plant losses a lot of water
It becomes flaccid
How do you know a plants cell are flaccid
You can see this in the wilting l, hanging leaves
What substances are stored in the vacuoles of plants
- Proteins are stored in the vacuoles developing seeds
- pigments like anthrocyanins (red, violet, blue)
- food reserves like mineral salts and sucrose
- excretory products may build up in the vacuole
How does a vacuole help with digestion
Sometimes the tonoplast looses its partial permeability and the enzymes are released into the cell and the entire cell is digested (autolysis), leaving the cell wall surrounding a hollow cavity l. Xylem tissue is formed this way
