B1 Cells Flashcards
What is resolution in imaging?
Ability to distinguish between 2 separate points in image
What is magnification?
How much bigger an image compared to actual object
What is the cell wall structure?
Outer layer of plant cells made of cellulose
Where are proteins made?
Ribosomes
What do chloroplasts contain?
Chlorophyll for photosynthesis
What are the advantages of a light microscope?
Cheaper, easy to use, can observe live cells
What are the advantages of an electron microscope?
Higher resolution, higher magnification, detailed views
What are the disadvantages of a light microscope?
Low resolution, limited magnification
What are the disadvantages of an electron microscope?
Complex preparation
What is the maximum magnification of a light microscope?
x1500
Why must specimens be dead for electron microscopy?
Process requires vacuum, so can’t observe living cells
What is osmosis?
Movement of water molecules across a partially permeable membrane form an area of high water potential to an area of low water potential until equilibrium is reached
What happens to an animal cell in a more dilute solution?
The cell gains water by osmosis and may burst. This is called lysis
What happens to an animal cell in a more concentrated solution?
The cell loses water by osmosis and shrivels. This is called crenation
Total magnification
Eyepiece lens x objective lens
Active transport
Movement of substances low to high against a concentration gradient
Require energy from respiration ATP
Why does active transport need carrier proteins in cell membrane
Bind to substance, change shape and transport it across membrane
When is active transport used in gut
When there’s lower concentration of nutrients in the gut but higher concentration of nutrients in blood
What happens when there’s higher concentration of glucose/amino acids in gut
They diffuse naturally into the blood
When would concentration gradient be going the wrong way
When there’s a lower concentration of nutrients in the gut than in the blood
When can glucose be taken into bloodstream
When its concentration in the blood higher than in gut
Differences between diffusion, osmosis and active transport
Only active transport require energy
Only active transport requires carrier proteins
Only active transport movement of substance are low to high
How osmosis differs from diffusion
Osmosis is movement of water across partially permeable membrane from area of high water potential to area of lower water potential.
Diffusion is movement of molecules and doesn’t require membrane
Similarities diffusion, osmosis
Both passive
Both involve movement down a concentration gradient
What happens to a plant cell when it is placed in a more DILUTE solution?
Cell gains water by osmosis but does not burst
This cell is now turgid.
Why does a plant cell not burst when it is placed in a more dilute solution?
Cell wall
What happens to an plant cell when it is placed in a more CONCENTRATED solution?
The cell loses water by osmosis. The cell membrane pulls away from the cell wall. This is is called plasmolysis.
Give an example of molecules that move by active transport.
Mineral ions in soil enter root hair cells
Describe how mineral ions enter root hair cells from the soil
Mineral ions absorbed into root hair cells by active transport
Which moves ions from a low concentration in the soil to high concentration in root hair cells
This process requires energy from respiration and involves carrier proteins in cell membrane
How do you calculate % change in mass
(Final mass - initial mass) ÷ (initial mass) x 100
Prokaryotic cell
Simple cell without nucleus and membrane bound organelles
Eukaryotic cell
Complex cell with nucleus and membrane bound organelles
Prokaryotic cells examples
Bacteris, Archaea
Eukaryotic cells examples
Plant cells, animal cells, fungal, protists
Differences between prokaryotic and eukaryotic cells
Prokaryotic has no nucleus, eukaryotic does
Prokaryotic cells are smaller
Prokaryotic cells have smaller ribosomes
Prokaryotic cells size
0.1-5 hm
Euakrayotic size
10-100 hm
Prokaryotic cells divide
Binary fission
Eukaryotic cells divide
Mitosis
What type of DNA do prokaryotic cells have?
1 circular chromosome, NOT enclosed by a nucleus.
What type of DNA do eukaryotic cells have?
Many linear chromosomes enclosed by a nucleus
Flagella
Helps movement
Plasmids
Small circular DNA molecules that carry extra genes
What is the function of sperm cells?
Fertilise egg during sexual reproduction
What is the function of nerve cells?
Transmits electrical impulses.
What is the function of muscle cells?
Contract quickly to move bones
How are sperm cells adapted for their function?
Streamlined head and long tail to aid swimming
Many mitochondria supply energy to allow cell to move
The acrosome (top of the head) has digestive enzymes which break down outer layers of membrane of the egg cell
How are nerve cells adapted for their function?
The axon is long, enabling the impulses to be carried along long distances
Nerve endings have many mitochondria which supply energy to make neurotransmitters
How are muscle cells adapted for their function?
Special proteins slide over each other, causing the muscle to contract
Lots of mitochondria provide energy from respiration for contraction
Can store glycogen used in respiration
What is the function of xylem cells in a plant?
Transport water and mineral ions up the plant from roots to shoots.
What is the function of phloem cells in a plant?
Transports food (by translocation) from the leaves to other parts of the plant.
How are xylem cells adapted for their function?
Xylem cells hollow and joined end-to-end to form a continuous tube so water and mineral ions can move through
Lignin helps cell walls which help withstand pressure water
How are phloem cells adapted for their function?
Have few organelles so food can move faster
Have companion cell with mitochondria to supply energy
Cell walls of each phloem cell form sieve plates when they break down, allowing the movement of substances from cell to cell
Cover slip used for
Flatten sample and protect microscope lens
Staining (drop of iodine) used for
Highlight specific cell structures
Why add drop of water
Prevent specimen from drying out and transparency
Why cover slip lowered 45° angle
Avoid trapping air bubbles
Why press down cover slip
To spread sample evenly ensure thin enough for light to pass through
Coarse adjustment knob
Bring specimen to rough focus
Fine adjustment knob
Gives clearer image
Diaphragm
Controls amount of light reaches specimen
