cel biology Flashcards
What is the prokaryotic cell wall composed of?
peptidoglycan
How is genetic information stored in prokaryotic cell?
found free within the cytoplasm
chromosomal dna (single large loop of circular dna
plasmid dna
what are plasmid?
Small circular loops of dna found free in the cytoplasm and separate from the main dna
carry genes that provide genetic advantages eg antibiotic resistance
What is the order of magnitude?
Power to the base 10 used to quantify and compare size 
what is a micrometer
1 x 10 -6
what is a nanometre
1 x 10 -9
The additional cell components found in plant cell
chloroplasts, permanent vacuole, cell wall
what is the function of the nucleus
control cellular activities
describe the structure of the cytoplasm
Fluid component of the cell
Contains organelles, enzymes and dissolved ions and nutrients
what is the function of the cytoplasm?
Site of cellular reactions, e.g. first stage of respiration
Transport medium
what is the function of the cell membrane?
Controls the entry and exit of materials into an out of the cell
what is the function of the mitochondria?
Sites of latest stages of aerobic respiration in which ATP is produced
what is the function of ribosomes?
joins amino acids in a specific order during translation for the synthesis of proteins
What is the plant cell wall made of?
Cellulose
what is the function of the plant cell wall
Provides strength, prevent self bursting when water enters by osmosis
what does the permanent vacuole contain
cell sap (a solution of salt, sugar, and organic acids)
What is the function of the permanent vacuole?
supports the cell ,maintaining its turgidity 
What is the function of chloroplast?
Sight of photosynthesis
at what point in their life cycle to most animals cells differentiate?
Early in their life cycle
for how long do plant cells retain the ability to differentiate?
Throughout the entire life-cycle
how do bacteria multiply?
Binary fission
how often do bacteria multiply?
Once every 20 minutes if enough nutrients are available and the temperature is suitable
State two ways in which bacteria can be grown
Nutrient broth solution
colonies on an agar gel
What nutrients make up a nutrients broth solution?
all nutrients required for bacteria to grow, including nitrogen for protein synthesis, carbohydrates for energy and minerals
what are uncontaminated cultures of microorganisms needed for?
Investigating disinfectant and antibiotic action
describe the preparation of an uncontaminated culture using aseptic technique
- Use pre-sterilised plastic petri dishes or sterilised glass petri dressage and agar gel before using with an autoclave.
- Pour the sterile agar gel into the petit dish and allow time to set.
- Sterilised the inoculating loop by passing it through a Bunsen burner flame.
- The inoculating loop into the solution of microorganisms and make streaks with the loop on the surface of the agar.
- Put the lid on the Petry dish and secure with tape. Label accordingly and then turn and start upside down.
- Incubate the culture at 25° in School laboratories.
why must the petri dish display be secured with adhesive tape and the whole dish put upside down?
stop bacteria in the air contaminating the culture
The lid is not fully sealed to prevent the growth of anaerobic bacteria in a lack of oxygen
Upside down to prevent condensation from farming and dripping down onto the colonies
why are cultures incubated at 25° in School laboratories?
Harmful pathogens are less likely to grow at this temperature
what are chromosomes made up of?
Chromosome consist of DNA molecules combined with proteins. They contain genes which provide the instructions for protein synthesis.
what is a gene
A section of DNA which codes for protein
what are the main stages of the cell cycle?
Replication of DNA and synthesis of organelles
Mitosis
Division of cell
why is mitosis important?
Produces identical cells which all have the same genetic information
Produces additional cells for growth and repair
Describe the first stage of the cell cycle
longest stage– cells grow and increase in mass, replicate and synthesise more organelles e.g. mitochondria, ribosomes
Describe the second stage of the cell cycle
Each chromosome in a pair is pulled to opposite poles of the cell, then the nucleus divides
Describe the third stage of the cell cycle
The cytoplasm and cell membrane divide – two identical data cells are produced
what is the function of stem cells in embryos?
 embryonic stem cells can replicate themselves and differentiate into many other type of cells. Embryonic stem cells may be able to treat conditions such as paralysis and diabetes by dividing to replace damage cells.
What is the function of stem cells in adult bone marrow?
Adult stem cells can differentiate into several cell types to replace dead or damaged tissues.
For example, bone marrow stem cells can confirm many different types of blood cell
what is the function of stem cells in plant meri stems?
Meristem cells retain the ability to differentiate into any type of plant cell throughout their lifespan – they can differentiate into any cell which is required by the plant
what is therapeutic cloning?
A cloning method where an embryo is produced with the same genetic make up as the patient. The stems are which originates from the embryo will not be rejected by the patient’s immune system, so can be used to treat certain medical conditions.
what are the advantages of cloning plants using Meristem cells?
can prevent rare plants from becoming extinct
Can produce large numbers of plants with a favourable characteristic
Can produce identical parts for research
what are issues associated with the use of stem cells?
Many embryonic stem cells are from aborted embryos – some people may have ethical/religious objection
Development of stem cells therapies is slow, expensive and difficult
Adult stem cells infected with viruses could transfer infections to patients
If stem cells do not have similar genetic makeup to the patient, an immune response could be triggered
what is diffusion?
The net movement particles from an area of high concentration to an area of lower concentration
what are three main factors that affect diffusion?
Concentration gradient – larger gradient, faster diffusion
Temperature – higher temperature, faster diffusion
Surface area – larger surface area, faster diffusion
give examples of substances transported by diffusion in the lungs and the kidney
Lungs: oxygen diffuses into the blood from the lungs and carbon dioxide diffuses into lungs from the blood, both down the concentration gradient
Kidney: diffuses from cells into blood plasma so it can be excreted in the urine
how a single celled organisms adapted for diffusion
They have a larger surface area to volume ratio – maximise the rate of diffusion of molecules to meet the organisms needs
what are four factors increase the effectiveness of gas exchange surface?
Large surface area
Thin membrane (short diffusion path)
Efficient blood supply – animals
Ventilation – animals
What is osmosis?
The movement of water from a dilute solution to a concentrated solution for a partially permeable membrane
what is meant when a solution is isotonic to a cell?
The concentrations of the external and internal solutions are the same
what is meant when a solution is hypotonic to a cell?
The concentration of the external solution is higher than the of the internal solution
What may happen when an animal cell is placed in a very hypotonic solution?
Water moves into the south, causing it to burst
what may happen when an animal cell is placed in a very hypertonic solution?
What moves out of the cell causing it to shrivel up?
how do plant leaves and stems remain rigid?
Turgor pressure – water moves in by osmosis , causing the vacuole to swell and the cytoplasm to press against the cell wall. 
what may happen when a plant cell is placed in a very hypertonic solution?
water moves out of the cell by osmosis and the vacuole and cytoplasms decreases in size. The cell membrane may pull away from the cell wall, causing the cells to become plasmolysed
What is active transport?
The movement of molecules from a more dilute solution to more concentrated solution against a concentration gradient, using energy from respiration
how do you plant root hair cells use active transport?
root hair cells use active transport to take up mineral ions from a more dilute solution in soils.
Ions such as magnesium and nitrates are required for healthy growth
how is active transport used to absorb the products of digestion?
active transport is used to transport glucose for the lower concentration in the to a higher concentration in the blood. Glucose is then transported to the tissues where it can be used in respiration. 
