Chapter 3 - Cell Structure Flashcards
What structures are included in the eukaryotic cells for animals?
- nucleus
- mitochondria
- rough endoplasmic reticulum (RER)
- smooth endoplasmic reticulum (SER)
- golgi apparatus
- lysomes
- ribosomes
- cell surface membrane
Describe the nucleus and its function
- nuclear envelope surrounding chromatin + nucleoplasm
* FUNCTION: stores genetic info to make protein and makes ribosome
Describe the mitochondria and its function
- double membrane
- inner is highly folded (cristae)
- FUNCTION: synthesis energy rich ATP molecules during aerobic respiration
Describe the rough endoplasmic reticulum and its function
- network of interjoined sheets studded with ribosomes
* FUNCTION: ribosomes synthesis proteins and channels transport these proteins
Describe the smooth endoplasmic reticulum and its function
- Soft surface and tubular appearance
* FUNCTION: synthesis, store and transports lipids
Describe the golgi apparatus and its function
- from RER then excretes to cell-membrane
* FUNCTION: Modifies proteins or lipids and packages them into vesicles for export
Describing lysosome and its function
- contains hydroletic enzymes
* FUNCTION: Fuses worn out organelles/enzymes digest organelles
Describe ribosomes and its function
- Contains rRNA and protein
- Occurs in cytoplasm or RER
- FUNCTION: Makes proteins
Describe cell-surface membrane and its function
- fluid Mosaic model
* FUNCTION:Controls the entry and exit
Calculate magnification
Image/actual (IAM)
What structures are included in eukaryotic cells for plants?
- cell wall
- chloroplast
- Vacule
Describe a cell wall and its function
- polysaccharides (cellulose)
- thin layer called middle lamellar makes boundary between adjacent cells and cernents adjacent cells
- FUNCTION: mechanical strength to prevent bursting of cell allowing only water to pass
Describe chloroplasts and its function
- chloroplast envelope with double plasma membrane and highly selective
- FUNCTION: harvesting sun light - carries out photosynthesis
Describe a vacule and its function
•FUNCTION: stores H2O
What is a transmission electron microscope?
Passes electrons through specimen giving 2-D images
What is the scanning electron microscope?
Passes electron over the surface of specimens given 3-D imaging (low resolution)
What is an advantage of electron microscope?
High resolving power as electrons have a shorter wavelength than light microscopes
What are disadvantages of a lecture microscopes?
- Systems must have a vacuum - Cannot observe living specimen
- complex staining – yet picture not coloured
- specimen must be thin
- may contain artefact - From the way specimen prepared changing appearance
- expensive
Describe the process of ultracentrifugation
•tissue homogenised in a blender in a solution which is: cold (inactivate enzyme)/isotonic (stops gaining/losing water)/buffered(keep the pH the same)
•tube span at high speed (1000 revs min^-1)
•pellet 1 - nucleus
•supernate removed (all except nuclei)
•run at higher speed
•pellet 2 - chloroplast/mitochondria
Repeat
What’s the fluid left after the cells are broken up by homogeniser releasing organelles from cell?
Homogenate
The two types of electron microscopes?
- Transmission electron microscope
* Scanning electron microscope
When using a light microscope we can measure the size of objects using…………….
An eyepiece graticule
To calibrate an eyepiece graticule you need to use a special microscope slide called a ……………..
Stage micrometer
Describe cell specialisation
It’s cell adapted to have a particular function and perform it to make it more efficient
Describe a tissue
A collection of similar cells for a specific function
Describe an organ
A collection of tissues to perform a variety of functions
Put an order in organ, cells, tissues and organs system.
Cells, tissues, organs and organ system
Given two examples of a tissue
- Epithelial tissue - found in animals and consists of sheets of cells
- Xylem – found in plants transporting water and minerals ions through the plant
Give two examples of an organ
- muscle – to churn up the stomach contents
* Palisade mesophyll - made up of leaves palisade cells that carry out photosynthesis
Give three examples of an organ system
- The digestive system – digests and processes food
- Respiratory system - useful breathing and gas exchange
- The circulatory system - pumps and circulates blood
Compare a prokaryotic and eukaryotic cell:
Prokaryotic cell – no nucleus/DNA is not associated with proteins/some DNA may be found in circular strand (plasmid)/no membrane/no chloroplast/ribosomes are smaller/cell wall made out of murine
Eukaryotic cell – distinct nucleus/do you need Societie proteins/no plasmid/DNA is linear/mitochondria are presents/chloroplast are present/ribosomes are larger
Name the cell structures in a bacterial cell
- cell wall
- capsule
- cell-surface membrane
- circular DNA
- plasmid
Define the role of the cell wall in a bacteria
Physical barrier that exclude certain substance and protects against mechanical damages
Define the role of a capsule in a bacteria
Protects bacteria from other cells and helps groups of bacteria to stick together
Define the role of cell-surface membrane in the bacteria
Controls what enters and exits chemically
Define the role of circular DNA in bacteria
Genetic information for replication of bacteria cells
Define the role of plasmid in a bacteria cell
Possesses genes that may aid aid survival of bacteria in at this condition
What structures are in the virus?
- attachment protein
- capsid
- lipid envelope
- matrix
- reverse transcription
- genetic material
What is mitosis?
Produces two daughter cells that have the same number of chromosomes as the parent cell and each other
What is meiosis?
Produces for daughter cells, each with half the number of chromosomes of the parents cell
What are the five stages of mitosis?
- interphase
- prophase
- metaphase
- anaphase
- telophase
What can you use to remember the mitosis stages?
IPMAT
Describe the interphase stage
- Growth
- DNA REPLICATION ( 1 chromosome = 2 chromatids)
- Replicates ATP and organelles
- Chromosomes invisible
Describe the prophase stage
- Chromesomes become visible (Short/condense)
* Nuclear envelope disappears
Describe the metaphase stage
• chromosomes attached to spindle fibres at the centromere
Describe the anaphase stage
- Spindle fibres contract
- chromatids separate to opposite poles
- Energy from mitochondria
Describe the telophase stage
- Chromatids reached piles
- Nuclear envelope forms two clusters
- Cytoplasm divides
What are the three stages of the cell cycle?
- nuclear division
- cytokines
- interphase
What is an object?
The material placed under the microscope
What is an image?
The appearance of the material viewed under the microscope
What is resolution?
How well a microscope can distinguish between two points that are close together
Maximum resolution of a light microscope
0.2 micrometres
Maximum magnification of a light microscope
1500 x
Maximum resolution of electron microscopes
0.0002 micrometres
Maximum magnifiation of electron microscopes
1,500,000 x
What are artefacts?
Things that you can see on the microscope but aren’t part of your specimen
How many micrometres are in a millimetre?
1,000
How many nanometres are in a micrometre?
1,000
How to calibrate a microscope?
1) Divide total length of stage micrometre by how many intervals to find one micrometre unit
2) Find a point where the two lines are equal
3) Work out how many micrometre units equal how many eyepiece units
4) Convert the stage micrometre units to micrometres
5) Divide stage micrometre units by eyepiece units to find the value of one eyepiece unit
6) This can be used in calculations
What is cell fractionation?
The process where cells are broken up and different organelles they contain are separated out
What happens during ultracentrifugation?
The filtrate is poured into a test tube, placed in the centrifuge and spun slowly
The heaviest organelles sink to the bottom, forming the pellet, whilst the rest of the organelles stay suspended in a fluid called the supernatant
The supernatant is drained off, poured into another test tube and spun at a higher speed
The next heaviest organelles form the pellet and are removed
The process repeats until the desired organelle forms the pellet, which can then be studied
What are grana?
Stacks of thylakoid membranes inside chloroplasts
What is the stroma?
A matrix where the sugars are synthesised during photosynthesis
