Module 2.1.1 - basic components of living systems Flashcards
What is resolution?
The smallest distance between two points that can still be seen as two points.
Name the 6 parts on a microscope
- objective lens
- eyepiece lens
- stage
- light source
- coarse focusing wheel
- fine focusing wheel
What does the coarse focusing wheel do?
Moves the stage up and down
What does the fine focusing wheel do?
Changes how clear the object is
What does stain do?
Increases contrast as different cellular components take up stain to different degrees
Components become more visible and easier to identify
What is a dry mount slide?
Viewing solid specimens with no water under a microscope
Living tissue e.g. hair, pollen, dust, insect parts
What is a wet mount slide?
Viewing specimens in liquid under a microscope, cover slip is added at an angle
Allows aquatic organisms to be viewed
What is a squash slide?
Wet mount is first prepared, pressure is applied to squash the sample to make it think enough for light to pass through
E.g observing mitosis in root meristems
What is a smear slide?
The edge of a slide is used to smear a sample creating a thin, even coat on another slide
Cover slip is added
E.g. observing cells within blood
What does staining a slide do?
Increased contrast as different cellular components take up stains to different degrees.
Components become more visible and easier to identify.
What are +ve charged stains attracted to?
-ve materials in cellular cytoplasm, staining the components.
what do -ve charged stains do?
repelled by -ve cytosol, dye stays outside of cells so they stand out against background.
What is differential staining?
used to distinguish between 2 types of organisms that would be hard to identify.
Gram positive
thick peptidoglycan layer that absorbs surroundings, even toxins.
Gram negative
thinner cell walls so lose the stain, therefore stained with safranin dye to make them appear red.
What does the Acid fast technique do?
distinguishes between mycobacterium and other bacteria.
How do electron microscopes work?
they use beams of electrons which have shorter wavelengths than light , resulting in a higher resolution.
What do you do to get from metre - millimetre - micrometre - nanometre - picometre?
Times by 1000
What do you do to get from picometre - nanometre - micrometre - millimetre - metre?
Divide by 1000
Give the advantages and disadvantages of electron microscopes
+ x500,000 magnification
+ cell ultrastructure visible
- very expensive
- specimens can be damaged by electron beams
- complex preparation can leas to artefacts
Name the 3 types of electron microscopes
Light, TEM, SEM
What is a TEM magnification?
x1,000,000
What is SEM magnification?
x150,000
What is a light microscopes magnification?
x2000
What is TEM resolution?
0.5nm
What is SEM resolution?
3-10nm
What is a light microscopes resolution?
200nm
Which microscope can see in 3D?
SEM
Which microscope can see in colour?
Light microscope
What does LSC stand for?
Laser scanning confocal microscope
What type of sample can each microscope view?
Light - living and dead
SEM - dead
TEM - dead
Why is a light microscope easier to use?
Requires less training, easy preparation
Why are SEM and TEM hard to use?
They are large, need to be installed, require training to use, complex preparation
What can LSC microscopes be used for?
Diagnose eye diseases and develop new drugs
What microscope has a beam of electrons transmitted through the specimen?
Transmission electron microscope (TEM)
What microscope has a beam of electrons sent across the surface of the specimen?
Scanning electron microscopes (SEM)
What covers the surface of every cell and surrounds most organelles?
Membrane
What do membranes do?
- allow selected molecules to move in and out of cell
- allows cell to change shape
What does the nucleus consist of?
genetic material, chromatin, bound in a nuclear membrane
What is chromatin?
DNA and histone proteins
What happens in the nucleolus?
Ribosome synthesis and ribosomal RNA
What do nuclear pores do?
Allow mRNA in and out
What is transcribed in the nucleus?
Ribosomal RNA
What attaches to the rough endoplasmic reticulum?
Most ribosomes where they translate mRNA into proteins
What is the Cisternae?
Flattened sacs of the ER that transport the translated mRNA proteins
What does the smooth endoplasmic reticulum do?
Has no ribosomes but is involved in the transport of proteins, production and storage of carbohydrates, lipids and other molecules
How are vesicles form?
The membrane of the ER continually buds off
Where are proteins/other molecules formed on the ER transported to?
Golgi apparatus
What does the Golgi apparatus do?
Modifies molecules and packages them for specific destinations in or out of the cell
What are some Golgi vesicles?
Lysosomes, containing enzymes that break down old organelles or infectious bacteria
Others transport proteins to elsewhere in the cell or eject them by exocytosis
What are mitochondria?
energy generating organelles
How is the cristae formed on mitochondria?
Out of the 2 surrounding membranes, the inner layer folds inwards to form the cristae
What does the cristae project into?
The matrix
What is the inner membrane of mitochondria coated in?
Enzymes which catalyze the reactions of aerobic respiration to produce ATP (adenosine triphosphate)
How is ATP produced?
The enzymes on the inner membrane of mitochondria catalyze the reactions of aerobic respiration
What are microtubules?
Main component of a cells cytoskeleton
What do microtubules do?
Connect the cell’s organelles to each other to keep them in place, can also alter their length to affect the shape of the cell or cause it to move
What do the centrioles do?
Coordinate the nucleation and growth of microtubules in all eukaryotes accept the higher plants
Give an example of a microtubule organizing center (MTOC)
Centriole
What is the secondary element of the cytoskeleton?
A network of very fine actin filaments
What is a flagellum?
Sticks out from the cell’s surface and is surrounded by the plasma membrane
What does cilia do?
Beat to power cell movement or to move fluid across the cell’s surface
What is cilia?
short hair-like outgrowths on the surface of a cell
What do flagellum contain?
2 microtubules in the center and 9 pairs around the edge
What do microtubules do?
Contract to move the flagellum
Where do plant cells gain all energy from?
Sunlight as cells in their leaves contain many chloroplasts
What is a prokaryotic flagellum made of?
Protein flagellin, arranged in a helix
What is the cell wall of a plant made of?
Polysaccharide cellulose and can function as a carbohydrate store by varying the amount of cellulose it holds
What are the pores in the cell walls of plant cells called?
Plasmodesmata that connects 2 cells together by their cytoplasm
How does the cell wall help a cell?
Gives support and structure
By the Plasmodesmata connecting 2 cells together by their cytoplasm’s do?
Enables the exchange and transport of substances
What do chloroplasts use to build sugars?
CO2, H2O and light energy
What type of membrane do chloroplasts have?
A double membrane
What is the double membrane of a chloroplast filled with?
A liquid called the Stroma and contains sacs of Thylakoid membranes called Grana
What are Thylakoid membranes the site for?
Photosynthesis
What type of vacuoles do plants have?
Permanent vacuoles
What type of vacuole do animal cells have?
Temporary vacuole
What do vacuoles consist of?
A membrane called tonoplast, filled with cell sap, a watery solution of different substances, including sugars, enzymes and pigments
What is the cell said to be when the vacuole is full of sap?
Turgid
How does the vacuole help the cell?
Keeps it firm by pushing everything else to the edge of the cell
What is a tonoplast?
Partially permeable of the vacuole
What is a amyloplast?
Double membrane bound sac containing starch granules
What domains can prokaryotic cells be divided into?
Bacteria
Archaea
In what cell is DNA suspended freely in the cytoplasm?
Prokaryotic cell
How big are bacteria cells?
1.5 micrometers
How many membranes does bacteria have?
1
What do bacteria contain?
Cell wall
DNA in cytoplasm
Chromosomes
Some have flagella
Ribosomes
What size are bacteria’s ribosomes?
Small
What shape are nucleoides?
Irregular shaped region and contains all/most the genetic material
What doe nucleiods control?
The cell, including reproduction
Where does ATP production take place?
Mesosomes
Where does transcription and replication take place?
Nucleoid
What are most pathogenic bacteria surrounded by?
A mucous-like protective layer called a capsule
What is a capsule usually composed of?
Polysaccharides and also contains water to protect against desiccation/ drying out
What does the bacterial capsule do?
Protects bacteria from viruses or attacks from a host organism’s immune system
What are flagella?
Long helical tubes extending out of the end of the cell wall, which rotates to provide locomotion
What are flagella powered by?
Protein motors
How far can flagella propel bacteria?
At a rate of more than 50 lengths per second
What is bacterial conjugation?
The transfer of genetic material from 1 bacterium to another
What are pili?
Hollow protein structures used during bacterial conjugation
How are the microtubules arranged at the length of flagellum or cilium?
9 + 2 pattern
How are the microtubules arranged at the base of flagellum or cilium?
Have a different arrangement
How do microtubules help the flagella move?
The microtubules slide past each other, causing the flagella to bend and straighten
What are plasmids?
Small continuous loops of DNA
Why are plasmids commonly used in genetic engineering?
To make copies of genes or large quantities to proteins or hormones
By plasmids being replicated independently of a bacterium’s chromosomal DNA, what may occur?
An advantage to the replica, such as antibiotic resistance
