B1- cell biology Flashcards
What are eukaryotics cells?
Eukaryotic cells are complex and include both plant and animal cells
Example of a prokaryotic cell?
e.g bacteria.
Eukaryotes are what?
They are organisms that are made up of eukaryote cells
A prokaryote is what?
Is a prokaryotic cell (a single celled organism)
What is the animal cell made up of?
A nucleus-hold DNA and controls the activities of the cell
Cytoplasm-the gel like substance where most chemical reactions take place
Cell membrane-allows what goes in and out
Mitochondria-where aerobic respiration takes place
Ribosomes-protein is made
What does the plant cell have that the animal cell doesn’t?
Cell wall-supports the cell and strengthens it
Vacuole-contains cell sap a weak solution of sugar and salt
Chloroplast -photosynthesis takes place (makes food for the plant)
Bacteria cells are what type of organism?
Prokaryotes
Structure of bacteria cell
-cell wall
-cell membrane
-cytoplasm
-bacteria cells don’t have a true nucleus instead have singular circular strands of DNA that float freely in the cytoplasm
-one or more ring of DNA called plasmids
-does not contain mitochondria or chloroplast
Magnification equation
Magnification=image size divide by real size
A specimen is 50 micrometers wide.Calculate the width of the image of the specimen under a magnification of x100.Give answer in mm
Image size=100x50
5000=micrometer
5=mm
Microscopy practical
Look at cgp book page 13
Cell differentiation is?
Is the process by which a cell changes to become specialised for its job
Why do cells differentiate?
As cells change they develop different subcellular structures and turn into different types of cells which allows them to carry out specific functions.
What are cells that are undifferentiated called?
Stem cells
One example of a specialised cell
Sperm cell-is to carry the male DNA to the female DNA.Function is it has long tail and streamlined head to swim quickly and have a lot of mitochondria for energy
Specialised cells
Nerve cell,muscle cells ,root hair cell ,phloem and xylem cells
Look in cgp book 14
Chromosomes contain what information and what are they?
Contain genetic information
-most cells in your body have a nucleus that contains genetic material in the form of chromosomes and are coiled up lengths of DNA molecules
How many chromosomes does a person have?
46 chromosomes in total
23 from each parent
Growth and DNA replication
1)in a cell that not dividing the FNA is all spread out in long strips
2)before it divides the cell has to grow and increase
3)then duplicates its DNA
Mitosis
4)the chromosomes 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
5)membranes form around each of the sets of chromosomes, these become nuclei of the two new cells-nucleus is divided
6)Lastly the cytoplasm and cell membrane divide.the cell has now produced two new daughter cells-they contain same DNA
Stem cells
Check page16 cgp
What is diffusion?
The spreading out of particles from an area of higher concentration to and area of low concentration
How to speed up the rate of diffusion?
Bigger concentration gradient
Higher temperature because they have more energy to move around faster
What’s the clever thing about cell membrane?
Don’t actually allow what goes in and out of the cell but really the substances can move in an out of cells through diffusion.
What can fit through the gaps of the cell membrane?
Oxygen,water,amino acid and glucose
What can’t?
Protein and starch
Osmosis is what
The diffusion of water molecules from an area of higher water concentration to and area of low water concentration
What’s a partially permeable membrane?
It’s just one with very small holes in that only water molecules can fit through and bigger molecules like sucrose can’t
What happens when there is to much water on one side of the net flow?
There is more water on one side that on the other, there is a steady net flow of water into the region with fewer water molecules into the stronger sugar solution meaning the strong solution gets more dilute and the water tries to even up the concentration on either sides of the membrane
What’s active transport?
When the concentration gradient is the wrong way around causing it to go from an area of low concentration to and area of high concentration
Where’s active transport found?
Root hair cells and gut
Describe a root hair cell
1)The cells on a plant root grow hairs which stick out into the soil
2)Each branch of root will be covered in millions of these microscopic hairs
3)This gives the plant a large surface area for absorbing water and mineral ions from the soil
4)Plants need these mineral ions for healthy growth
5)The concentration of minerals is usually higher in the root hair cells than in the soil around them
How does a root hair cell take in minerals using active transport?
Active transport allows the plant to absorb minerals from a very dilute solution against a concentration gradient (very essential for its growth) but actuve transport needs energy from respiration
What’s another example of active transport in humans?
In the gut there is a lower concentration gradient then in the blood stream meaning they have to use a process called active transport.This process allows nutrients with a lower concentration gradient to diffuse into the blood stream.
An example of active transport happening inside the gut?
Glucose can be taken into the bloodstream when it’s concentration gradient is already higher that in the gut.
Where does gas exchange take place?
Lungs
How does the alveoli work?
-Air comes in through the nose and into the air sac (stays in the alveolus)
-from that air oxygen diffuses into the blood capillary where red blood cell are found
-then the co2 diffuses from the red blood cell to the alveolus and leaves the air sac.
What are the air sacs in the lungs called?
Alveoli-where gas exchange takes place
How is the alveoli specialised to maximise the diffusion of O2 and Co2?
-an enormous surface area
-very thin walls
-good blood supply
Where is the villi found?
Small intestine
What do they do?
They increase the surface area in a big way in order for that digested food to be absorbed much more quickly into the blood
What happens when carbon dioxide diffuses into the air spaces?
Carbon dioxide diffuses into the air spaces within the leaf then it diffuses into the cells where photosynthesis takes place
What’s the stomata?
Little holes which carbon dioxide diffuses in through
What diffuses out from the stomata?
Oxygen and water vapour
What are guard cells?
Controls the stomata
Check more on page 22 cgp for the gills of a fish
More exchanging substances
