B1 Cell Biology Flashcards
What are the two types of cells?
Eukaryotic (plant and animal)
Prokaryotic (bacteria)
What are the differences between eukaryotic and prokaryotic cells?
Prokaryotic cells are much smaller than eukaryotic cells.
Eukaryotic cells contain membrane bound organelles and a nucleus containing genetic material while prokaryotic do not.
What is the prokaryotic cell wall composed of?
Peptidoglycan
What is genetic information stored in a prokaryotic cell?
Found free within the cytoplasm as:
Chromosomal DNA (single large loop of circular DNA)
Plasmid DNA
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
What is order of magnitude?
A power to the base 10 used to quantify and compare size
What is a centimetre?
1x10^-2 metres
What is a millimetre?
1x10^-3 metres
What is a micrometer?
1x10^-6 metres
What is a nanometre?
1x10^-9 metres
List the similarities of both plant and animal cells
Nucleus
Cytoplasm
Cell membrane
Mitochondria
Ribosomes
List the cell components of a plant cell
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 (first stage of cellular respiration)
Transport medium
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
What is the function of the permanent vacuole?
Supports the cell maintaining its turgidity
What is the function of chloroplasts?
Site of photosynthesis
Describe how sperm cells in animals are adapted to their function
Tail enables movement
Haploid nucleus contains genetic information
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
Merged cells in skeletal muscle allow muscle fibre contraction in unison
What are chromosomes made up of?
Chromosomes 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 a protein
How many chromosomes are found in the nucleus of human body cells?
46
How many chromosomes are found in the nucleus of gametes?
23
How are chromosomes arranged in the nucleus of a human body?
Arranged in pairs (46 chromosomes, 23 pairs)
What are the three 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 DNA and synthesise more organelles (e.g. ribosomes, mitochondria)
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 daughter cells are produced
What is a stem cell?
An unspecialised cell which is capable of differentiating into other cell types and or self renewal
What is the function of stem cells in embryos?
Embryonic stem cells can replicate themselves and differentiate into many other types of cells.
Embryonic stem cells may be able to treat conditions such as paralysis and diabetes by dividing to replace damaged 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 form many different types of blood cell
What is the function of stem cells in plant meristems?
Meristems stem 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 makeup as the patient.
The stem cells which originate from the embryo will not be rejected by the patients immune system so can be used to treat certain medical conditions
What are the advantages of cloning plants using meristem stem cells?
Can prevent rare plants from becoming extinct
Can produce large numbers of plants with a favourable characteristic
Can produce identical plants for research
What are issues associated with the use of embryonic stem cells?
Sourced from aborted embryos (ethical religious objection)
Development of stem cell therapies is slow, expensive and difficult
Adult stem cells infected with viruses could transfer infections to patients
If donor stem cells do not have a similar genetic makeup to the patient an immune response could be triggered
Define nucleus
Diameter 10um a nucleus membrane surrounds it, controls the activities of the cell. Contains genes that carry the instructions for making proteins.
Define cytoplasm
Jelly- like material that contains dissolved nutrients, salts and organelles. Where most chemical reactions take place
Define cell membrane
Surrounds the cell. It’s structure is permeable to some substances but not to others. It therefore controls the passage and movement of substances. Into and out of the cell
Define mitochondria
Small structure (1-2 um long, 0.2-0.um in diameter) in the cytoplasm. Where aerobic respiration takes place
