B1 - Cell Biology Flashcards
What are all living things made out of?
Cells
What are animal cells made out of?
Eukaryotic and animal cells
What are Prokaryotic cells?
Smaller and simpler cells
What are eukaryotes?
Organisms made up of eukaryotic cells
What is a prokaryte?
Prokaryotic cell (single-celled organism)
Animal cell structure (subcellular structures)
Nucleus Cytoplasm Cell membrane Mitochondria Ribsomes
Nucleus
Contains genetic material that controls the activities of the cell
Cytoplasm
Gel like substance where chemical reactions happen. Contains enzymes that control chemical reactions
Cell membrane
Holds the cell together and controls what goes in and out
Mitochondria
Most of the reactions for aerobic respiration take place. Respiration transferes energy that the cells need to work
Ribsomes
Where proteins are made in the cell
Plant cell structure
Rigid cell wall
Permanent vacuole
Chloroplasts
Rigid wall cell
Made of cellulose. It supports the cell and stregnthens it
Permanet vacuole
Contains sell sap, a weak solution of sugar and salts which helps keep the cell turgid
Chloroplasts
- Where photosynthesis occurs.
- Contains chlorophyll which makes the plant green and absorbs light for photosynthesis.
What are the differences in size between bacterial cells and plant/animal cells?
Bacterial cells are smaller
Bacteria cell structure
They are prokaryotes
- cell membrane
- cell wall
- cytoplasm
- plasmids
- singular strand of DNA which floats freely
Do bacteria have nucleui?
No
What does Bacteria use to represent itself
A single strand of DNA that floats freely in cytoplasm
Plasmids
Small rings of DNA
Microscopes (nos)
Powerful microscopy techniques to see things that you can’t see with the naked eye
How do light microscopes work? (Nos)
Use light and lenses to form an image of the specimen and magnify it
How do electron microscope work? (Nos)
Use electrons instead of light to form an image
Resolution (nos)
The ability to distinguish between 2 points
Magnification = (nos)
Image size/ real size
Why are microscopes useful? (Nos)
You can see things that you can’t see with the naked eye
How should you prepare your slide for a light microscope? (Onion cell) (nos)
1) Add a drop of water in the middle of the clean slide
2) Cut up an onion amd seperate it out from the layers
3) Place tissue onto the slide
4) Add a drop of iodine solution
5) Place a cover slip (tilt and lower it to avoid air bubbles)
Parts of a light microscope (nos)
- Eyepiece
- Coarse adjustment knob
- Fine adjustment knob
- Lenses
- Stage
- Light
How to use a light microscope (nos)
1) clip slide
2) adjust the knobs
3) look down eypiece
4) adjust accordingly
Differentiation
The process by which a cell changes to specilaised its job
What happens when cells change during differentiation?
Thy develop subcellular structures and turn into different types of cells which allows them to carry out specific functions
Why do cells differentiate in matue animals?
Repair and replace cells
Difference between animal and plant differentiation
Animal cells lose the ability to differentiate, however, plant cells do not lose this ability
Give some examples of specialised cells
- Sperm
- Nerve
- Muscle
- Root
- Phloem
- Xylem
Sperm cells
Get male DNA to the female DNA Has a long tail Streamlined head Lots of mitochondria Enzymes to digest through egg membranes
Nerve cells
- Carry electrical signals from one part of the body to another
- Long
- Branched connections at the ends to connect to other nerve cells
- Form a network
- Axons
- Dendrites
- Myelin sheath for insulation
Muscle cell adaptations
- Contract quickly
- Long
- Contain lots of mitochondria (to transfer energy needed for contractions)
- Can store glycogen
- Special proteins that slide over each other making the fibres contract
Root Hair Cells
Big surface area for absorbing water and mineral ions
Phloem and Xylem cells
Transport substances such as food and water around plants
Form long tubes
Gollow
Very few subcellular structures
How is genetic material stored?
Form of chromosones
What are chromosones?
Coiled up lengths of DNA molecules
What do chromosones carry?
Large number of genes
What do genes control?
The development of different characteristics
Why does the body store 2 copies of each chromosome?
So it can store one from the organism’s ‘mother’ and ‘father’
How many chromosomes do you have in total in one cell?
46 (23 pairs)
Cell cycle
Body cells in multicellular organisms divide to produce new cells
Mitosis
The cell divides into 2 identical cells with the same number of chromosomes
Mitosis allows …
Growing and replacing cells that have been damaged
2 main stages of cell cycle
Growth and DNA Replication
Mitosis
Stages of Growth and DNA replication
1) DNA spread out into long strips
2) Cell has to grow and increase amount of subcellular structures (elements of a cell)
3) Duplicates DNA - each arm of the chromosome is copied and forms x shaped chromosones
Stages of mitosis
1) Chromosones line up st the centre of the cell and cell fibres pull them apart
2) Membranes go around each set of chromosomse and become 2 new nuclei
6) They cytoplasm and cell membrane divide
What can embryonic cells do?
It can turn into any cell
Stem cells
They can divide to turn into many different undifferentiated cells
Where can you find stem cells?
Baby embryo
Bone marrow
Why are some people against stem cell reserch?
Because they can become infected with a virus which could be passedd on to the patient and make them sick
Human embryos shouldn’t be used for experiments
How can stem cells be ussed in plants?
Stem cells are found in meristerms and they can grow into any type of plant cell
They can be used to grow rare species of plants and for disease resistance
Quick and Cheap
Diffusion (nos)
The spreading out of particles from a high concentration to a lower concentration
What substances can diffusion be diffused? (Nos)
Solutions and gases
What factors can give a faster diffusion rate? (Nos)
Biggr concentratin gradient
Higher temperature
What do cell membranes do that can relate to diffusion? (Nos)
The particles move randomly but if there are more particles on one side of the membrane, theres a net movement from one side to another
How can you increase the diffusion rate in cell membranes? (Nos)
Larger membrane surface area
Why do organisms use diffusion? (Nos)
To get rid of waste products
How do humans use diffusion to get rid off waste products? (Nos)
Gas exchange
Urea diffuses from cells into blood plasma
What does surface to volume area show?
How easy it is to exchange substances with its environment
How do you calculate volume to surface area ratio?
Surface Area : Volume
Why can gases easily diffuse across the cell membrane in single-celled organisms?
They have a large surface area compared to their volume
Why is it hard for multicellular organisms to diffuse substances?
Have a small surface area in ratio to their volume
Give some ways that exchange surfaces are adapted to maximise effectiveness
Thin membrane
Large surface area
Lots of blood vessels
Gas exchange surface areas
Give some adaptations in alveoli that help with gas exchange diffusion
Lots of air sacs called alveoli Enormous surface area Moist lining Very thin walls A good blood supply
Give some adaptations in the small intestine to maximise diffusion
Single layer of surface cells
Very good bloody supply to assist quick absorption
Villi
How are leaves adapted to diffuse efficiently?
Water vapour and oxygen diffuse out through the stomata
Guard cells close the stomata if the water is being lost faster than it is being replaced by the roots
The walls of the cells form another exchange surface
The air spaces inside the leaf increase the surface area
Osmosis
Osmosis is the movement of water molecules across a partially permeable membrane from a region of a lower water concentration (dilute solution) to a region of higher water concentration (concentrated)
Partially permeable membrane
A membrane with very small membranes in it meaning only small tiny molecules can pass through them
Why does a cell transfer water out of it into syrup?
Because the cell has a higher water concentration causing water to move through a partially permutable membrane (osmosis) into the lower concentrated solution. This means the more strong sugar solution becomes more dilute
Give some root hair cells adaptions
Loads of them which allow a large surface area for absorbing water and mineral ions from the soil. The concentration of minerals is usually higher in the root hair cells than in the soil around them
Why do root hair cells not use diffusion?
Minerals should move out of the root hairs if they followed the rules of diffusion. The cells must use another method to draw them in
What is active transport?
The process in which allows the plant to absorb minerals from a very dilute solution, against a concentration gradient. But active transport needs energy from respiration to work
Does active transport work in humans?
Yes
Where is active transport used in the human body?
In the gut but a higher concentration of nutrients in the blood
