B1 Cell Biology Flashcards
All living things are made of
Cells
Eukaryotic cells are
Complex
Prokaryotic cells are
Smaller and simpler
Example of prokaryotic cells
Bacteria
Example of eukaryotic cells
Animal and plant cells
The different parts of a cells are called
Subcellular structure
What is the nucleus
Contains genetic material .Genetic material controls what the cell does
What is the cytoplasm
Where most of the chemical reactions take place
What is the cell membrane
Controls what enters and leaves the cell
What ia mitochondria
Where most aerobi respiration happens.Respiration transfers energy that the cell needs to work
What are ribosomes
Ribosomes are where proteins are made
Plant cells have all the bits that an animal cells has but also have
A cell wall
A permanent vacuole
Chloroplast
What is the cell wall
Made of cellulose.It supports the cell and strengthens it
What is the permamnent vacuole
Contains cell sap
What is chloroplasts
Where photosynthesis happens.Photosynthesis makes food for plants
Light microscopes can be used to look at cells.They let us see
Large subcellular structures such as the nucleus
Electron microscopes have a higher resolution than
Light microscopes
Electron microscopes have a higher magnification than light miscroscopss.They can let us see
Very small things such as ribosomes and plasmids
What is the formula for working out the magnification of an image
Magnification = image size over real size
What ia differentiation
The process by which cells change to become specialised
As cells change they develop different
Subcellular structures
Most differentiation occurs as an organism
Develops
What are stem cells
Cells that are undifferentiated
Most animal cells can only differentitate at an
Early stagebof an animal’s life
But lots of plants can differentiate
For the whole of the plant’s life
Cells that differentiate in adult animals are mainly used for
Repairing and replacing cells
Two examples of specialised cells
Sperm cells
Nerve cells
How are sperm cells specialised
A sperm cell has a tail to help it swim to the egg .
Has loads of mitochondria.These provide energy to swim
How are nerve cells specialised
Nerve cells are long to cover more distances in the body.
They have branches at the end to connect with other nerve cells
The nucleus of a cell contains chromosomes.What are chromosomes
Chromosomes are colied up lengths of DNA molecules
Each chromosome carries a large number of
Genes
Different genes control the development of
Different characteristics e.g hair colour
The cell cycle has two stages what are they
Growth and DNA replication
Mitosis
What is mitosis
The stage of the cell cycle when the cell divides is called mitosis
Cell cycle - growth and DNA replication
The cell grows and increases the number of subcellular structures such as ribosomes and mitochondria.
The DNA is replicated ( copied ) so there’s one copy for each new cell
Cell cycle - Mitosis
Cell is now ready for dividing.The chromosomes line up at the centre of the cell.The two arms of each chromosome are pulled apart to opposite ends of the cell.This divides the nucleus.Each set of chromosomes become the nucleus of a new cell.Cytoplasm and cell membrane divide too .The cell has nowmproduced two new cells.They both contain the same DNA x they’ re identical
What is diffusion
Diffision is the spreading out of particles from an area of higher concentration to an area of lower concentration
Where does difusion happen
Diffusion happens in solutions or gases
Difference in concentration is called the
Concentration gradient
The bigger the concentration gradient the faster the
Diffusion rate
What thing affects the diffusion rate
Temperature
Cell membranes let stuff diffuse in and out of the cell.Only very small molecules can fot through
Cell membranes such as oxygen, amino acids and water
Big molecules such as starch and proteins can’t fit through
Cell membrane
What is osmosis
Osmosis is the movement of water molecules across a partially permeable membrsne from a less concentrate solution to a more concentrated solution
What is a partially permeable membrane
Just one with very small holes in it
What is active transport
The movement of substances from an area of low concentration to an area of high concentration , against the concentration gradient
Sometimes there is a lower concentration of nutrients in the gut than there is blood.When this happens body
Uses active transport to move the nutrients from an area of low concentration to an area of high concentration
For active transport to work it needs
Energy from repiration
Multicellular organisms like animals have a small surface area compared to
Volume
Multicellular organisms can’t normally exchange enough substances across their
Outside surface area
How are the exchange surfaces adapted to allow enough of different substances to pass through
They have a thin membrane ( so substances only have a short distance to diffuses )
They have a large surface area ( somlots of substances can diffuse at once )
Exchange surfaces in aniamls have lots of blood vessels ( stuff can get in and out of the blood quixkly )
Gas exchange surfaces in animals are ventilated too
Where are oxygen and carbon dioxide exchanged
In the lungs
The lungs contain what which is where gas exchange happens
Contain millions of little air sacs callsed alveoli
Alveoli are specialised for the diffusion of oxygen and carbon dioxide
A large surface area
Very thin walls ( so gases don’t have far to difuse )
A good blood supply
Inside the small intestine isncovered in villi.Villi increase the surface area so that digested food is absorbed more quickly in the blood
Single layer of surface cells
A very good blood supply
Plants need to take in carbon dioxide for photosynthesis and get rid of
Oxygen and water vapour
The underneath of the leaf is an exchange surface .It is covered in small holes called stomata.Carbon dioxide diffuses
Through the stomata into the leaf
The size of the stomata are controlled by
Guard cells
The flattened shape of the leaf increases the
Area of its exchange surface
What is the gas exchange surface for fish
Gills
