Biology B1 - cell structure and function Flashcards
3 facts about the cell theory that I need to know
- all living things are composed of cells.
- cells are the basic units of all living things.
- all cells come from pre - existing cells.
what are characteristics of cells ?
plant and animal bodies are composed of cells .
each cell is a living unit requiring nutrients and oxygen and producing waste products.
cells are just only outside the range of human vision.
the largest cells are about 0.1 nm..
plant cells in general are bigger than animal cells .
what are 3 things that most cells contain ?
Nuclus , cytoplasm , cell membrane
what is a eukaryote ?
a eukaryote is any organism consisting of one or more cells that contain DNA in a membrane - bound nucleus , separated form the cytoplasm.
what are the 4 eukaryotes ?
Animals
Plants
fungi
protists.
what is the description and function of the nucleus ?
description - largest organelle
function - contains genetic material , responsible for protein synthesis , cell division.
what is the description and function of the nuclear envelope ?
description - perforated by nuclear pores of about 50 - 100 nm diameter.
function - 2 membranes that surround nucleus , allow exchange with cytoplasm.
what is the description and function of the nucleolus ?
description - darkly staining region inside nucleus.
function - manufacture ribosomes.
what is the structure of the smooth and rough endoplasmic reticulum
- consists of a series of flattened membranes that from tubes in the cytoplasm .
- rough endoplasmic reticulum is studded with ribosomes
- smooth endoplasmic reticulum does not have ribosomes.
what is the function of the smooth and rough endoplasmic reticulum ?
rough endoplasmic reticulum transports proteins that were made on attached ribosomes. these proteins may be placed on the cell surface membrane or secreted from the cell.
smooth endoplasmic reticulum is involved in making lipids that the cell needs .
what is the structure of the golgi appartus
a stack of membrane bound flattened sacs that are constantly changing.
what is the function of the Golgi apparatus
receives proteins from the endoplasmic reticulum and modifies them.
it may add sugar molecules to the proteins.
it packs the modified proteins into vesicles that can be transported
they may go to the surface of the cell to be secreted.
what is the structure of mitochondria ?
- may be sausage or spherical shape.
- they have a double membrane.
- cristae are in the inner membrane they are folds.
- central part of the mitochondrion is called the matrix.
what is the function of the mitochondria ?
it produces adenosine triphosphate (ATP) in the mitochondria during respiration.
what is the structure of lysomes and examples ?
structure :
- spherical sacs surrounded by a single membrane.
- small in size
Examples - white blood cell lysomes break down invading microorganisms.
what is the function of lysomes ?
contain powerful digestive enzymes to break down materials such as long chain fatty acids and hydrogen peroxide.
what is the structure of ribosomes ?
tiny organelles about 20nm in diameter with no membrane.
some are found in the cytoplasm and some are attached to the endoplasmic reticulum.
what is the function of ribosomes ?
protein synthesis occurs.
they connect amino acids.
what is the structure and function of chloroplasts ?
large double membrane bound , found only in plants .
structure - it is the site of photosynthesis .
what is the structure of the permanent vacuole ?
filled with water or cell sap.
large in plant cells.
what is the function of the permanent vacuole ?
to provide mechanical support for the plant and its cells. to allow movement of water through the roots.
what is the structure of the plasma membrane ?
double layer found in all cells. consists of proteins and cholesterol.
what is the function of the plasma membrane ?
controls the exchange of substances between the cell and its environment.
what is the structure of centrioles ?
organelle that is not bound by a membrane . found only in animal cells.
what is the function of centrioles ?
organises microtubules. involved in cell division.
what is the structure of cilia / flagella ?
thin extensions on the cell surface.
cilia is short and many and flagella is long and few.
what is the function of cilia / flagella ?
used for movement.
what is the structure of microvilli ?
finger like projections of the cell surface membrane.
100 nm in diameter.
found in small intestine and the kidney.
what is the function of microvilli ?
increases the surface area of the cell surface membrane.
what is the function and structure of the cytoplasm ?
- it refers to all living parts of the cell.
- consists of membrane bound organelles and cytosol , the fluid part of the cytoplasm.
The Cytoskeleton refers to the network of protein fibres fund within the cells that gives structure and shape to the cell and also moves organelles around inside the cells.
what is an Amyloplast ?
it is a double membraned organelle , used for manufacturing and storing starch.
what is a plasmodesmata ?
holes in the cell walls to adjacent cells where the cytoplasm touches, used for transport and communication between cells.
key facts about bacterial cells
bacterial cells do not have their genetic material enclosed in a membrane . this types of cell is called Prokaryotic. they also have additional small pieces of genetic material in their cells called plasmids.
comparing eukaryotic cells with prokaryotic cells ?
eukaryotes have cell surface membranes. cells walls are made of cellulose. eukaryotes have ribosomes of any size. DNA is found in the nucleus. ATP production takes place in mitochondria . eukaryotic cells have flagella and cilia , they are often multicellular organisms. always have a cytoskeleton , cell division is by meiosis or mitosis.
Whereas
prokaryotic cells have only 1 membrane . the cell wall is made up of peptidoglycan . prokaryotic cells have smaller ribosomes and the DNA is found in an area called the nucleoid. some prokaryotes have flagella, they are always unicellular organisms , they don’t have a cytoskeleton, and cell division is by binary fusion.
comparing gram positive and gram negative bacteria
gram positive : thicker and smooth cell wall . The colour under the microscope is purple. there is an absent outer membrane . very susceptible to antibiotics. thick and multi-layered peptidoglycan layer. very low lipid content . absent space between lipid layers.
Gram Negative : thinner waxy cell wall , pink colour under the microscope, present outer membrane , thin and single layered peptidoglycan layer , 20 to 30 percent lipid content , present space between lipid layers.
what are the steps involved in gram staining ?
Staining with crystal violet.
Fixing the dye.
Applying a decolourizer.
Counter-staining, usually with safranin.
name 6 parts of a microscope ?
Eyepiece lens , the Handle , Objective lens , Stage , Focusing Wheel, Light
what is the history of developing the microscope
- first compound microscope , 1595.
- Leuwenhoek microscope 1600.
- Hooke microscope 1670.
- first interchangeable magnification , 1884 .
- Modern light microscope.
- Electron microscope.
facts about the microscope and about carrying it .
microscopes are fragile and are expensive.
we must treat microscopes with respect. the microscope is carried by the arm with a hand supporting the base.
how to use a light microscope ?
- move the stage to the lowest position.
- Select the objective lens with the lowest magnification.
- Place the glass slide you want to observe on the stage and secure with the clips.
- looking from the side use the fucus knob to bring the stage to the highest position.
- look through the eyepiece lens and use the focus knob until you see object.
- select an objective lens with higher magnification if needed and repeat focus steps.
what do light microscopes allow us to observe ?
we can observe with a light microscope prokaryotic cells and large structures such as mitochondria in eukaryotic cells.
what are the principles of optical microscopes ?
First and still common.
Shows a 2D image. Uses visible light to create an image. Resolution limit to 200nm . Magnification up to x2000. Light is sent from a light source through a specimen , the image of which is magnified by the glass lenses.
what are the advantages of optical microscopes ?
Live organisms.
True colour.
what are the principles of Transmission electron microscopes ?
The electron beam travels through the specimen to a detector below. Maximum magnification is up to x 2 , 000, 000 .
resolution is 0.1 nm .
This allows for higher resolution and magnification, but a 2D image.
what are the principles of scanning electron microscopes ?
The electron beam hits the specimen and is scattered into a detector. The maximum magnification is x 50 , 0000 and the maximum resolution is20 nm . The electrons are scattered off the surface of the specimen and so produce a 3D image.
what are the limitations of a light microscope ?
- low resolution .
- specimen must be very thin.
-only magnifies up to x1500 .
-can’t see smaller organisms.
what are the limitations of a transmission electron microscope ?
- cannot look at living material.
- must be in a vacuum.
- specimen must be very thin.
- Image 2D
- does not produce coloured image.
what are the limitations of a scanning electron microscope ?
- must be in a vacuum.
- must be dead.
- can’t see organelles.
- does not produce coloured image.
- low resolution.
define the term magnification ?
magnification is the degree to which the size of an image is larger than the image itself.
define the term resolution ?
resolution is the degree to which it is possible to distinguish between two objects that are very close together.
what is the magnification equation ?
Magnification = size of image / size of real object
how do you convert from millimetres to micrometres ?
x 1000
What eukaryote does not have a cell wall ?
Animals
Which organelles are present in plant cells but not in animal cells ?
Vacuole
Chloroplasts for photosynthesis
Cell wall made of cellulose
Give 4 organelles that you would find inside an animal cell ?
- nucleus
- ribosomes
- mitochondria
- cell membrane
what are two most fundamental group of cells ?
Prokaryotic cells and eukaryotic cells
what are the common features of prokaryotes ?
- cytoplasm that lack membrane - bound organelles
- no nucleus
- Circular DNA molecules called plasmid’s
- A polysaccharide capsule surrounding the cell
- one or more flagella
what is the name given to the rings of DNA found in prokaryotes ?
Plasmids
What colour do Gram - positive bacteria appear under a microscope ?
Purple
What type of molecule are cell surface membranes made up of ?
Phospholipid
What are the components of a phospholipid ?
- A lipid molecule
- Two fatty acid chains
- A phosphate - containing group.
What shape are eukaryotic chromosomes ?
Linear structures
What process specifically takes place in ribosomes ?
Protein synthesis
What is the main function of the Golgi apparatus ?
Packaging and tagging proteins and lipids .
What is the name of the model that describes the structure of plasma membranes ?
Fluid mosaic model
What is the name of the membrane that surrounds the vacuole ?
Tonoplast membrane
Which organelle stores starch ?
Amyloplast
What is the name for the small cylindrical organelles pictured ?
Centrioles
Which cell type is between 0.1 and 5.0 micrometres in diameter ?
Prokaryote
Which cell type can form multicellular organisms ?
Eukaroyte
Which organelle do fungal cells lack ?
Chloroplasts
What is the plant cell wall made of ?
Cellulose
What cellular component does not have a double membrane ?
Lysomes
What is the name of the fluid - filled membrane sacs found within the chloroplasts ?
Thylakoids
Where are ribosomes found bond to a membrane ?
Rough endoplasmic reticulum
Which prokaryotic feature allows the exchange of genetic information ?
Pili
Important facts about specialised cells ?
Red blood cells are specialised to carry oxygen,
Palisade cells have a long , upright shape
Organs are contained within organ systems
The female reproductive system is an organ system
What are specialised cell organised into ?
Tissues
What is an example of an organ system ?
The female reproductive system
