b1 cell biology Flashcards
differences between prokaryotes and eukaryotes
1) prokaryotes have a single loop of DNA called plasmids, whereas eukaryotes have a nucleus
2) prokaryotes are much smaller in size
3) prokaryotes have a bacterial cell wall, made from peptidogyclan
4) prokaryotes dont have chloroplasts or mitochondria
what do animal cells contain?
nucleus
mitochondria
ribosomes
cytopasm
cell membrane
what do plant cells contain?
nucleus
rigid cell wall
cell membrane
mitochondria
ribosomes
cytoplasm
vacuole
chloroplasts
function of nucleus?
controls genetic material and controls the activities of the cell
function of mitochondria?
where most of the reactions for aerobic respiration take place and providing energy for the rest of the cell
function of ribosomes?
where protein synthesis takes place, making proteins
function of the cell membrane?
hold the cell together and controls what goes in and out of the cell
function of the cytoplasm?
gel-like substance where most of the chemical reactions take place. also contains enzymes that control these chemical reactions
function of cell wall?
made of cellulose and supports the cell and strengthens it
function of vacuole?
contains cell sap, a weak solution of sugar and salts
function of chloroplasts?
where photosynthesis takes place, making food for the plant. also contains chlorophyll which absorb light energy
orders of magnitude?
10x bigger= 10^1
100x bigger= 10^2
1000x bigger= 10^3
10x smaller= 10^-1
how to estimate the area of a sub-cellular structure?
treat it as as a regular object and use the equation:
area= length x width
what is a tissue?
a layer of cells with a similar function
what is an organ?
a group of tissues working together to perform a similar function
what is an organ system?
a group of organs working together to perform a vital function
how are sperm cells adapted for its function?
1) long tail so the sperm can move to the ovum.
2) the acrosome is packed with digestive enzymes to eat through the top layer of the ovum
3) full of mitochondria to provide energy for the sperm cell to swim longer distances
how are nerve cells adapted for function?
1) long axons, enabling impulses to be carried through long distances
2) a lot of dendrites to branch connections and form other nerve cells
3) a lot of mitochondrian to supply energy to make neurotransmitters
4) myelin sheath to prevent electrical current from exiting the axon and to maximise electrical current transmission
how are muscle cells adapted for function?
1) proteins called myosin and actin which slide over one another so the muscles can contract
2) a lot of mitochondria for re respiration and contraction
3) contains glycogen for respiration
how are root hair cells adapted for its function?
1) large surface area, due to roots, for more osmosis
2) mitochondria to provide energy for active transport of minerals
how are xylem cells adapted for its function?
1) the lignin which causes the cell to die, they become hollow and are joined end-to-end to form a long tube that the mineral ions can flow through.
2) the lignin is deposited in spirals so the cells can withstand the water pressure
how are phloem cells adapted for its function?
1) cell walls form sieve plates when they break down, allowing movement of substances from cell-to-cell
what happens as an organism develops?
cells in the body differentiate to become different cells and to complete different functions
when do animal cells usually differentiate?
at an early stage
when do plant cells usually differentiate?
at any stage of their life
how have microscopy techniques developed overtime?
1) light microscopes use light and lenses to observe individual cells and large sub-cellular structures
2) electron microscopes use electrons to form an image. it provides a higher magnification and resolution.
how has the electron microscope increased understanding in sub-cellular structures?
because the electron microscope has a much higher magnification and resolution,this means that we can study cells in much more finer details, therefore increasing scientists understanding of sub-cellular structures
equation for magnification?
size of image// size of actual object
how can bacterial cells divide and many times can they divide?
1) binary fission
2) once every 20 minutes
methods in which bacteria can be grown?
1) nutrient broth solution
2) grown s colonies on agar gel plates
why are uncontaminated cultures required?
investigating disinfectants and antibiotics
method of culturing?
1) sterilise petri dish using an autoclave
2) sterilise inoculating hoops by passing it through a fire
3) seal the lid of the petri dish (not completely) with tape
4) store petri dish upside down
5) incubate at 25 degrees
why should you sterilise the petri dish?
to prevent contamination with other (unwanted) micro-organisms. as they may compete with the desired bacteria for space and nutrients and xreate a new pathogen
why should you sterilise inoculating loop with a fire?
to kill unwanted organisms
why should u seal the lid (not completely) with tape?
sealing it stops air borne micro-organisms from entering and contaminating the culture but sealing it all the way could lead to harmful anaerobic bacteria growing
why should the petri dish be stored upside down?
to prevent condensation from landing on the agar surface, disrupting growth
why should u incubate your culture at 25 degrees?
to prevent bacteria to grow at bodily temperatures which means they can enter a human and manage to survive, before causing potential harm
how to calculate cross- sectional colonies of bacteria?
pi x radius^2
what does the nucleus of an animal cell contain?
contains chromosomes made of DNA molecules.
Each chromosome carries a large number of genes
how are chromosomes in the body found?
in pairs
explain mitosis cycle?
1) sub-cellular structures are replicated and pulled to each end of the cell
2) chromosomes line up at the centre of the cell and cell fibres pull them apart. the chromosomes go to opposite ends of the cell
3) membranes form around eat set of the chromosomes, becoming the nuclei of the cell
4) cytoplasm and membrane divide, creating 2 daughter cells
why is mitosis important?
important in the growth and development of multicellular organisms
what are stem cells?
A stem cell is an undifferentiated cell of an organism which is capable of
giving rise to many more cells of the same type, and from which certain
other cells can arise from differentiation
what are the functions of stem cells in embryos?
to repair, or regenerate tissue and cells
what is the function of stem cells in adults?
repair damaged tissue and regeneration
what is the function of meristem cells?
a source of new cells to grow or replace specialised tissues
what types of cells can embryos make?
embryos can become almost any type of cell
what type of cells can bone marrow make?
mainly blood cells
what type of cells can meristem make?
any type of plant cell
what types of conditions could stem cells cure?
1) paralysis
2) amputees
3) diabetes
what happens in therapeutic cloning?
and embryo is produced with the same genes as the patient. therefore the embryo won’t be rejected by the patient’s body. this is effective with the treatment
what are the problems with the use of stem cells?
1) could transfer a viral infection
2) ethical reasons as some people may view the embryo as potential life
how can stem cells from meristems in plants can be used to produce clones of
plants quickly and economically?
1) Rare species can be cloned to protect from extinction.
2) Crop plants with special features such as disease resistance can be
cloned to produce large numbers of identical plants for farmers.
what is diffusion?
the movement of particles in a solution or gas. from a high conc to a low conc. moving down the conc gradient. no energy required
examples of substances in the body that are transported via diffusion?
1) oxygen for gas exchange
2) carbon dioxide for gas exchange
3) waste product of urea from cells into the blood plasma for excretion from kidneys
factors that affect the rate of diffusion?
1) concentration
2) temperature
3) surface are of membrane
how does an increase in concentration affect the rate of diffusion?
it increases the rate of diffusion as it increases the concentration gradient
how does the increase in temperature affect the rate of diffusion?
it increases the rate of diffusion as the heat increases the Ke of the particles, there they move around faster
how does the increase in surface area affect the rate of diffusion?
increases the rate of diffusion as there more space for the particles to diffuse past, therefore more particles will diffuse
what is osmosis?
the movement of water from a dilute solution to a concentrated solution through a partially permeable membrane. moving down the conc gradient. no energy required
what is active transport?
the movement of substances from a more dilute solution to a more
concentrated solution (against a concentration gradient). This requires
energy from respiration
what is the importance of active transport in plants?
allows mineral ions to be absorbed into plant root hair cells from very dilute solutions in the soil. plants require ions for healthy growth
what is the importance of active transport in humans?
allows sugar molecules to be absorbed from the lower concentrations in the gut into the blood which has a higher concentration. sugar molecules are used for respiration
why are mineral ions important for plant growth?
1) nitrate- used for the production of animo acids which form protein
2) magnesium- used for the production of chlorophyll which absorbs light energy for photosynthesis
