B1 Cell Biology Flashcards
what is a cell
The smallest unit of living matter
what organelles are found in plants only
chloroplasts, vacuole, cell wall
define the nucleus
contain genetic information which control the activities of the cell
define the cytoplasm
most chemical reactions take place here(controlled by enzymes)
define the cell membrane
controls the movement of substances into an out of a cell
define the mitochondria
most energy is released by respiration here
define ribosomes
where protein synthesis takes place
define the cell wall
strengthens the cell
define chloroplasts
contains chlorophyll which absorbs light energy for photosynthesis
define the permanent vacuole
filled with cell sap
name 3 advantages of light micropscopes
cheep to buy
colour images can be obtained
can view living specimens
name 3 disadvantages of light microscopes
limited magnification
depth of field is restricted
limited resoloution
name 3 advantages of electron microscopes
high resolution
greater depth of field
high magnification
name 3 disadvantages of electron microscopes
expensive to buy
living specimens cannot be obtained
images are black and white
what is the equation for magnification
magnifictaion = image size
actual size
define diffusion
the movement of substances from and area of high concentration to an area of low concentration down the divsion gradient, it is a passive process
what is a partially permeable membrane
where there is space fro a small volume of particles to enter or leave
define active transport
the movement of particles from an area of low concentration to and area of high concentration, against the division gradient using energy
define osmosis
the diffusion of water from a dilute to a concentrated soloution across a partially permeable membrane passive process
what is the risk assessment for the osmosis RPA 1
care should be taken
cutting potato cylinders
using electrical balance in the presence of water
what is the apparatus required for the osmosis RPA 1 (name at least 5 )
potato
ruler
10cm3 measuring cylinder
labels boiling tubes
a test tube rack
knife
salt soloution
distilled water
what is the method for the osmosis RPA2
- cut 3 potato cylinders and make sure the are all the same length
- measure and record the mass of each potato cylinder
- measure 10cm3 of the 0,5 salt solution and put into the first boiling tube label the boiling tube 0.5m salt
- do the same fro all salt solution
- add one potato cylinder to each boiling tube
- leave the potato cylinders in the boiling tubes overnight in the test tube rack
7.remove the potato cylinders from the boiling tubes and carefully blot them dry - re-measure the length and mass of each cylinder and record the meaurements on the table
- record the results on a graph
define DNA
the chemical from which chromosomes are made
genes
a small packet of information controlling a characteristic
chormesome
thread like structures holding genes
define mitosis
the division of cells to create 2 identical daughter cells
what are stem cells
undifferentiated cells meaning they have no specific function
what are embryonic stem cells
cells that can differentiate into any other type of cell
what are adult stem cells
have limited number of cells they and differentiate into
What are sperm cells specialised to do
Sperm cells are specialised for reproduction
What is the function of a sperm cell
To get the male DNA to the female DNA
What are two adaptations of a sperm cell
There are a lot of mitochondria in the cell to provide the energy it needs
It also carries enzymes in its head to digest through the egg cell membrane
What are nerve cells specialised for
Nerve cells are specialised for rapid signalling
What is the function of a nerve cell
To carry electrical signals from one part of the body to another
How are nerve cells adapted for their function
The cells along the cover more distance and have branched connections at their ends to connect other nerve cells and form a network throughout the body
How are muscle cells specialized for their function
Muscle cells are specialised for contraction
What is the function of a muscle cell
To contract quickly
How are muscle cells adapted to their function
The cells are long so that they have space to contract and they contain lots of mitochondria to generate the energy needed for contraction
How are root hair cells specialised for their function
Root hair cells are specialised for absorbing water and minerals
What is the function of a root hair cell
Root hair cells are cells on the surface of plant roots which grow into long hairs that stick out into the soil
How are root hair cells adapted to their function
They have a large surface area for absorbing water and mineral ions from the soil
How are phloem and xylem cells specialized for their function
Phloem and xylem cells are specialised for transporting substances
What is the function of phloem and xylem cells
Phloem and Dylan cells form phloem and xylem tubes, which transport substances such as food and water around plants to form the tubes. The cells are long and joined end-to-end
How are phloem and xylem cells adapted to their function
Xylem cells are hollow in the centre and phloem cells have very few subsellular structures so that stuff can flow through them
What are the three stages to cell growth and DNA replication
Step 1: in his cell that’s not dividing, the DNA is all spread out in Long strings
Step 2: before it divides, the cell has to grow and increase the amount of sub cellular structures such as mitochondria and
Step 3: the cell then duplicates its DNA– so there’s one copy for each new cell. The DNA is copied and forms x shaped chromosomes. Each ‘arm’ of the chromosome is an exact duplicate of the other
What are the three stages of mitosis
Step 1: the chromosomes line up at the center of the cell and cell fibers pull them apart. The two arms of each chromosome go to opposite ends of the cell
Step two: membranes form around each of the sets of chromosomes. These become the nuclei of the two new cells. The nucleus has divided
Step 3: lastly the cytoplasm and the cell membrane divide full stop the cell has now produced two new daughter cells. The daughter cells contain exactly the same DNA. They are identical. Their DNA is also identical to the parent cell
What are the two main stages of the cell cycle
DNA replication and mitosis
What is the stage of the cell cycle when the cell divides called
Mitosis
What do multicellular organisms use mitosis for
To grow or replace cells that have been damaged
How do prokaryotic cells reproduce
Binary fission
What are the four stages to binary fission
Step 1: the circular DNA and plasmids replicate
Step two colon The cell gets bigger and the circular DNA strands move to opposite ends of the cell
Step 3: the cytoplasm begins to divide and new cell walls begin to form
Step 4: the cytoplasm divides and two daughter cells are produced each daughter cell has one copy of the circular DNA but can have a variable number of copies of the plasminants
What is differentiation
Differentiation is the process by which a cell changes to become specialized for its job
What is a stem cell
An undifferentiated cell able to divide to produce lots more undifferentiated cell. They can differentiate into different types of cell depending on which instructions they’re given
Where are stem cells found
Stem cells are found in early human embryos. Adults also have stem cells but they’re only found in certain places like bone marrow
How can stem cells be used
Medicine uses adult stem cells cure disease. Embryonic stem cells can also be used to replace full p cells in sick people
What are some risks of using stem cells
Stem cells grown in a lab may become contaminated with a virus which could be passed on to a patient and make them even more unwell
What are some reasons why people are red against stem cell research
(1) some people are against stem cell research because they feel that human embryos shouldn’t be used for experiments since each one is a potential human life
(2) campaigners for the rights of embryos feel that scientists should concentrate more on finding and developing other sources of stem cells so people could be helped without having to use embryos
(3) in some countries stem cell research is banned, but it’s allowed in the UK as long as it follows strict guidelines
What part of a plant can stem cells be found in
Meristems
