1. cell Biology Flashcards
What are the two types of cells ?
-Eukaryotic (plant and animal)
-Prokaryotic (bateria)
What are the differences between eukaryotic and prokaryotic cells ?
Prokaryotic cells (bacterial cells) are much smaller than eukaryotic cells (plant and animal cells).
Eukaryotic cells contain membrane bound-organelles and a nucleus containing genetic material, while prokaryotes do not.
How is genetic information stored in a prokaryotic cell?
Found free within the cytoplasm as:
• Chromosomal DNA (single large loop of circular DNA)
• Plasmid DNA
- NOT ENCLOSED BY A NUCLEUS
What are plasmids ?
Small, circular loops of DNA found free in the cytoplasm and separate from the main DNA.
• Carry genes that provide genetic advantages e.g. antibiotic resistance.
What is order of magnitude ?
A power to the base 10 used to quantify and compare size
What is a centimetre (cm) ?
1 × 10^-2 metres
What is a millimetre (mm)?
1 × 10^-3 metres
What is a micrometre (um)?
1 × 10^-6 metres
What is a nanometre (nm)?
1 × 10^-9 metres
List the components of both plant and animal cells (5)
• Nucleus
• Cytoplasm
• Cell membrane
• Mitochondria
• Ribosomes
List the additional cell components found only in plant cells (3)
• Chloroplasts
• Permanent vacuole
• Cell wall
Other than storing genetic information , what is the function of the nucleus ?
Controls 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.
What is the function of the cell membrane?
Controls the entry and exit of materials into and out of the cell.
What is the function of the mitochondria ?
Site of later stages of aerobic respiration in which ATP is produced
What is the function of the 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
-Prevents the cell bursting when water enters by osmosis
What does the permanent vacuole contain ?
Cell sap ( a solution of salts , sugars and organic acids).
What is the function of the permanent vacuole ?
Supports the cells ,maintaining its turgidity
What is the function of chloroplasts ?
Site of photosynthesis
Describe how sperm cells in animals are adapted to their function ?
• Haploid nucleus contains genetic information.
• Tail enables movement.
• Mitochondria provides energy for tail movement.
• Acrosome contains enzymes that digest the egg cell membrane.
Describe how nerve cells in animals are adapted to their function
• Long axon allows electrical impulses to be transmitted all over the body from the central nervous system.
• Dendrites from the cell body connect to and receive impulses from other nerve cells, muscles and glands.
• Myelin sheath insulates the axon and speeds up the transmission of impulses along the nerve cell.
Describe how muscle cells in animals are adapted to their function
• Arrangement of protein filaments allows them to slide over each other to produce muscle contraction.
• Mitochondria to provide energy for muscle contraction.
Describe how root hair cells in plants are adapted to their function
• Large surface area to absorb nutrients and water from surrounding soil.
• Thin walls that do not restrict water absorption.
Describe how xylem cells in plants are adapted to their function
• No upper or lower margins between cells to provide a continuous route for water to flow.
Thick, woody side walls strengthen their structure and prevent collapse.
Strengthened by a substance called lignin
Describe how phloem cells in plants are adapted to their function
• Sieve plates let dissolved amino acids and sugars be transported up and down the stem.
• Companion cells provide energy needed for active transport of substances along the phloem.
What is cell differentiation ?
The process by which cells become specialised
Why is cell differentiation important ?
Allows production of different tissues and organs that perform various vital functions in the human body.
At what point in their life cycle do most animal cells differentiate ?
Early in their life cycle
For how long do plant cells retain the ability to differentiate ?
Throughout their entire life cycle
What is the purpose of cell division in mature animals ?
Repair and replacement of cells
What changes does a cell go through as it differentiates ?
Becomes specialised to enable a specific function to be performed by the cell.
Define magnification
The number of times bigger an image appears compared to the size of the real object
Define resolution ?
The smallest distance between two objects that can be distinguished
How does a light microscope work ?
Passes a beam of light through a specimen which travels through the eyepiece lens, allowing the specimen to be observed.
What are the advantages of light microscopes (4)
• Inexpensive
• Easy to use
• Portable
• Observe both dead and living specimens
What is the disadvantage of light microscopes?
Limited resolution
How does an electron microscope work ?
It uses a beam of electrons which are focused using magnets. The electrons hit a fluorescent screen which emits visible light, producing an image.
What is the advantage of electron microscopes ?
Greater magnification
Why do electron microscopes have a greater magnification and resolution ?
They use a beam of electrons which has a shorter wavelength than photons of light.
How have electron microscopes enabled scientists to develop their understanding of cells ?
• Allow small sub-cellular structures (e.g. mitochondria, ribosomes) to be observed in detail.
• Enable scientists to develop more accurate explanations about how cell structure relates to function.
What are the disadvantages of electron microscopes ?(4)
• Expensive
• Large so less portable
• Require training to use
• Only dead specimens can be observed
How can magnification be calculated ?
Magnification = size of image / size of real object
What is standard form?
A way of expressing numbers - written as a figure between 1 and 10 multiplied by a positive or negative power of 10.
Write 0.005 in standard form
0.005 = 5 × 10^-3
Write 10383 in standard form
10382 = 1.0382 x 10^4
