Flashcards in Cell Biology Deck (76):
What is a prokaryotic cells characteristics?
Small and simple
What is a eukaryotic cells characteristics?
Complex (bigger than prokaryotic cells)
Include all animal and plant cells
...organisms that are made up of eukaryotic cells
A prokaryote is...
...a prokaryotic cell - it is a single-celled organism.
What does an animal cell contain?
What does a plant cell contain?
What is the purpose of the nucleus?
It contains genetic material that controls the activities of the cell
What is the purpose of mitochondria?
These are where the most of the reactions for AEROBIC respiration take place.
Respiration transfers energy that the cell needs to work
What is the purpose of cytoplasm?
It is a gel-like substance where most of the chemical reactions happen.
It contains enzymes that control these chemical reactions
What is the purpose of the cell membrane?
It holds the cell together and controls what goes in and out
What is the purpose of ribosomes?
These are where the proteins are made in the cell
What is the purpose of the (rigid) cell wall?
It is made of cellulose.
It supports the cell and strengthens it together
What is the purpose of chloroplasts?
These are where photosynthesis occurs, which makes food for the plant.
They contain a green substance called chlorophyll which absorbs the light needed for photosynthesis
What is the purpose of the permanent vacuole?
It contains cell sap, a weak solution of sugar and salts
List the features of a bacteria cell
They are prokaryotes
They don't have a 'true' nucleus - they have a single circular strand of DNA that floats freely in the cytoplasm
They can contain one or more small rings of DNA called plasmids
They don't have chloroplasts or mitochondria
What does a bacteria cell contain?
Circular strand of DNA
Microscopes let us...
See things that we can't see with the naked eye
Light microscopes use ...
...light and lenses to form an image of a specimen and magnify it
They let us see individual cells and large sub cellular structures
Electron microscopes use...
...electrons to form an image.
They have a much higher magnification and resolution than light microscopes.
They let us see much smaller things in more detail.
What is the formula for magnification?
Magnification = image size / real size
/ = divided by
How do you prepare a slide to view onion cells?
1) add a drop of water to the middle of a clean slide
2) cut up and onion and separate it out into layers. Use tweezers to peel of some epidermal tissue from the bottom of one of the layers
3) using the tweezers l, place the epidermal tissue into the water on the slide
4) add a drop of iodine solution
5) place a cover slip on top.
What are the parts of a LIGHT microscope?
Coarse adjustment knob
Fine adjustment knob
High and low power objective lenses
What is differentiation?
Differentiation is the process by which a cell changes to become specialised for its job
Why do cells differentiate?
To become specialised
As cells change, they develop ...
(Differentiation + Specialisation)
...different sub cellular structures and turn into different types of cells. This allows them to carry out specific functions
Most differentiation occurs as an organism ...
When do animals loose the ability to differentiate?
At an early stage, after they have become specialised.
When do plant cells loose the ability to differentiate
Most plants cells don't ever lose this ability
What are cells that differentiate in mature animals mainly used for?
Repairing and replacing cells, such as skin or blood cells.
What are undifferentiated cells called?
Give 5 examples of specialised cells
Root hair cells
Phloem and Xylem cells
What are sperm cells specialised for?
What information can be given about sperm cells?
-The function of a special is to get the male DNA to the female DNA
-It has a long tail and a streamlined head to help it swim to the egg.
-There are a lot of mitochondria in the cell to provide the energy needed.
-It carries enzymes in its head to digest through the egg cell membrane
What are nerve cells specialised for?
What information can be given about nerve cells?
-The function of the nerve cell is to carry electrical signals from one lady of the body to another
-These cells are long (to cover more distance) and have branches connections at their ends to connect to the other nerve cells and form a network throughout the body
What are muscle cells specialised for?
What information can be given about muscle cells?
-The function of a muscle cell is to contract quickly
-These cells are long (so that they have space to contract) and contain lots of mitochondria to generate the energy needed for contraction
What are root hair cells specialised for?
What information can be given about root hair cells?
Absorbing water and minerals
-Root hair cells are Ella in the surface of plant roots, which grow into long "hairs" that stuck out into the soil
-This gives the plant a big surface area for absorbing water and mineral ions from the soil
What are phloem and xylem cells specialised for?
What information can be given about phloem and xylem cells?
-Phloem and xylem cells form phloem and xylem tubes, which transport substances such as food and water around plants
-To form the tube, the cells are long and joined end to end
-Xylem cells are hollow in the centre and phloem cells have very few subcellular structures so that stuff can flow trough them
Embryonic stem cells can turn into...
...ANY type of cell
What can undifferentiated cross (stem cells) do?
They can divide to produce lots more undifferentiated cells.
They can differentiate into different types of cell, depending on what instructions they're given.
Where are stem cells found?
In early human embryos
Where are adult stem cells found?
In certain places like bone marrow
What can adult stem cells turn into?
Only certain ones such as blood cells
How can stem cells be used in medicine?
Adult stem cells are already used to cure disease e.g stem cells transferred from bone marrow from a healthy person can replace faulty blood cells in the receiver.
Embryonic stem cells could also be used to replace faulty cells in sick people e.g you could make insulin-producing cells for people with diabetes.
Why are some people against stem cell research?
They feel that human embryos shouldn't be sued for experiments since each one is potential human life HOWEVER others think that curing patients who already exist and who are suffering is more important than the rights of embryos
How do stem cells produce identical plants?
1) stem cells are found in the meristems of plants
2) throughout the plants life cells in the meristem tissues can differentiate into any type of plant cell
3) these stem cells can be used to produce clones of whole plants quickly and cheaply
4) they can be used to grow more plants of rare species
5) stem cells can also be used to grow crops of identical plants that have desired features for farmers
What do chromosomes contain?
What are chromosomes?
Coiled up lengths of DNA molecules
How many pairs of chromosomes does a human cell have?
How many copies of each chromosomes do body cells normally have?
2, one from the organisms mother and one from its father
What is stage of the cell cycle called when the cell divides?
Why do body cells in multicellular organisms divide?
To produce new cells as part of a series of stages called the cell cycle
What do multicellular organisms uses mitosis for?
They use mitosis to grow or replace cells that have been damaged
What is the result at the end of the cell cycle?
Two new cells identical to the original cell with the same number of chromosomes
What are the two main stages of the cell cycle?
Growth and DNA replication
What are the stages of growth and DNA replication in the cell cycle?
Before mitosis, the cell has to grow and increase the amount of subcellular structures (such as mitochondria and ribosomes)
It then duplicates its DNA
What are the stars of mitosis in the cell cycle?
The chromosome line up at the centre of the cell and cell fibres pull them apart. the two arms of each chromosome go to opposite ends of the cell.
Membranes form around each of the sets. These become the nuclei of the two new cells.
Lastly, the cytoplasm and cell membrane divide
What happens in binary fission?
The cell splits into two
What are the stages of binary fission?
1) the circular NDA and plasmids replicate
2) the cells get bigger and the circular DNA strands moves to the opposite 'poles' (ends) of the cell.
3) the cytoplasm begins to divide and new cell walls begin to form
4) the cytoplasm dives and two daughter cells are produced
What is diffusion?
Diffusion is the movement of particles form and area do higher concentration to an area of lower concentration
Where does diffusion occur and why?
In solutions and gasses because the particles are free to move about randomly
How can you increase the rate of diffusion?
Having a higher temperature
Having a bigger concentration gradient
What do cell membranes do?
They hold the cell together but they let stuff in and out as well - only very small molecules can diffuse through cell membranes e.g oxygen
The is the rate of diffusion faster with a larger surface area of the membrane
Because mor else tickets can pass through at once
What Is osmosis?
Osmosis is the movement of water molecules across a semi/partially permeable membrane from an area of high concentration to an area of low concentration
What is active transport?
The movement of molecules from an area of low concentration to an area of high concentration.
In active transport, molecules move against the concentration gradient no therefore require an input of energy from the cell
Give an example of active transport being used in a plant?
Root hair cells take in minerals using active transport
Give an example of active transport in human body's
Active transport stops us from starving.
Active transport is used in the gut when there is a lower concentration of nutrients from the gut but a higher concentration of nutrients in the blood
Give an example of how cells can use diffusion to take in substances they need and get rid of waste products
- Oxygen and carbon dioxide are transferred between cells and the environment during gas exchange
- In humans, urea diffuses from cells into the blood plasma for removal from the body by the kidneys
What's the difference between single-called
Organisms and multicellular organisms when exchanging substances
I'm single-celled organisms, gases and dissolved substances can diffuse directly into the cell across the cell membrane because they have a large surface area compared to their volume, so enough substances can be exchanged across the membrane to supply the volume of the cell.
Multicellular organisms have a smaller surface area compared to their volume, so not enough substances can diffuse to supply their volume.
Multicellular organisms need an exchange surface for efficient diffusion
Exchange surfaces are adapted to maximise effectiveness.
What do they contain and why?
They have a thin membrane (shorter distance)
They have a large surface area (faster rate of diffusion)
In animals they have lots of blood vessels (to get stuff in and out of the blood quickly)
Gas exchange surfaces in animals are often ventilated
What is the job of the lungs?
To transfer oxygen to the blood and to remove waste carbon dioxide from it.
Where does gas exchange happen in the lungs?
In little air sacs called alveoli
How are the alveoli specialised to maximise the diffusion of oxygen and CO2?
-An enormous surface area
-A moist lining for dissolving gases
-Very thin walls
-A good blood supply
Where are villi found in the body?
Inside of the small intestine
What do the villi do?
They increase the surface area so that digested food is absorbed quicker into the blood
What do villi have?
A single layer of surface cells
A very good blood supply to assist quick absorption