A1CC1 Chapter 2 - Cell Structure and Organisation Flashcards
What is an organelle?
A specialised structure found within eukaryotic cells that carries out a specific function for the cell.
What is a eukaryoic cell?
Eukaryotes contain DNA in chromosomes in a nucleus, and possess membrane bound organelles. Eg: Plants and Animals.
What is the resolving power?
The minimum distance by which two points must be separated in order for them to be seen as two distinct points rather than one focused image.
What is the nucleus and its function?
An organelle responsible for containing the DNA for protein synthesis.
What is the structure of the nucleus?
It has a double membrane for which the outer membrane is continuous with the endoplasmic reticulum. This double membrane contains pores to allow for mRNA to leave the nucleus.
What is the nucleoplasm?
This is a part of the nucleus which contains chromatin. The chromatin is what condenses to form chromosomes during cell division.
What is the nucleolus and its function?
A small spherical body found in the nucleus. It is responsible for the production of mRNA and ribosomes.
What is mitochondria?
The site of aerobic respiration, producing ATP.
Describe and explain the structure of mitochondria? (2)
- Inner membrane which folds into structures called cristae. These provide a large surface area for the attachment of enzymes (eg: ATP Synthase).
- Fluid Filled Matrix containing lipids and proteins, 70s ribosomes and a small loop of DNA.
What is a prokaryote?
A single celled organism lacking membrane-bound organelles, such as a nucleus, with its DNA free in the cytoplasm.
What are chloroplasts?
Found in photosynthetic plants. They are the site of photosynthesis.
Simply name all of the structures present in a chloroplast. (7)
- Double Membrane
- Loop of DNA
- Thylakoid membrane
- 70s Ribosomes.
- Starch grain
- Fluid Filled Stroma
- Intergranal Lamella/thylakoid.
What is the structure of chloroplasts? (3)
The organelle is surrounded by a double membrane which contains a fluid-filled stroma with starch grains, 70s ribosomes and a circle of DNA.
What is a thylakoid?
A structure located in the chloroplast; a granum is multiple thylakoids stacked together.
What is the endoplasmic reticulum?
A system of double membranes forming interconnected flattened fluid filled sacs called cisternae, which are connected to the nuclear envelope.
What is the role of the endoplasmic reticulum?
The transport of materials through the cell.
What is the difference between rough and smooth endoplasmic reticulum?
Rough endoplasmic reticulums have ribosomes attached to the outer surface and once proteins are synthesised there they are transported via the cisernae.
Smooth endoplasmic reticulums lack the ribosomes so instead are involved in the synthesis and transport of lipids.
What are ribosomes and their function?
Made up of rRNA and protein. Found in the cytoplasm. Their role is to assemble proteins during translation.
What is the structure of the ribosomes?
No membrane surrounding.
Consist of two subunits.
What does the small and large subunits of the ribosomes do?
The small subunit contains a mRNA attachment site.
The large subunit contains two tRNA attachment sites.
How do ribosomes differ between cells?
In eukaryotic cells there are the large 80s ribosomes.
In prokaryotic cells there are smaller 70s ribosomes.
What is the golgi body?
Similar to the endoplasmic reticulum, but more compact in shape. It is a stack of curved cisternae.
What is the function of the golgi body?
Vesicles containing polypeptides bud off the rough endoplasmic reticulum, and fuse with the golgi body for export.
What are lysosomes?
Small single membraned vacuoles that are pinched from the golgi apparatus containing the digestive enzyme lysozome.
What is the role of lysosomes?
- To digest worn out organelles in the cell.
- To digest foreign material that has been engulfed by phagocytosis. Eg: Bacteria in white blood cells.
What are centrioles, their structure and their function?
Present in plant cells and protoctista. Consist of two rings of microtubules at right angles to eachother. They organise the microtubules that make the spindle during cell division.
What is the vacuole?
A fluid filled organelle (cell sap) in plants. Surrounded by the tonoplast.
What is the role of the vacuole?
To support soft plant tissues
To store chemicals such as glucose and amino acids.
What is the cell wall?
Made up of cellulose (in plants).
What is the cell wall’s function? (3)
- Transport of water and dissolved molecules and ions through gaps in the cellulose fibres. Known as the apoplast pathway.
- Communication between cells via pores in the cell wall which allows strands of the cytoplasm called plasmodesmata to pass. This hence allows water to go the symplast pathway.
- Provide strength to the cell and create turgor due to resistance from vacuole expansion.
Highlight 6 differences between animal and plant cells.
- Plants have cell wall surrounding the membrane whereas animal cell does not.
- Plants have chloroplasts present, whereas animals cells do not.
- Plant cells have a large, permanent, single vacuole whereas animal cells have small, temporary vacuoles.
- Plant cells have no centrioles whereas animal cells do.
- Plant cells have plasmodesmata whereas animal cells do not.
- Plant cells have starch grains present for energy storage whereas animal cells have glycogen granules for energy storage.
What are prokaryotic cells, their structure. (7)
Lack true nucleus.
Single strand of DNA.
Cytoplasm and cell wall present.
Mesosome (site of aerobic respiration)
Plasmids
70s Ribosomes
Flagellum (in some bacteria)
What is a virus?
An organism without a cytoplasm, organelles or any chromosomes. They only contain nucleic acid (DNA or RNA) surrounded by a protein coat, called the capsid.
How does a virus work?
The ‘inert’ virion is incapable of reproducing or synthesising without the use of the hosts cytoplasm. When they burst out of cells and reinfect healtht cells, damage occurs.
What is the equation for magnification?
A = I/M
What are the levels of organisation?
Cells - Tissues - Organs - Organ Systems
In terms of levels of organisation, what is the difference between single celled and multicellular organisms?
Single celled organisms carry out all life processes within one cell, whereas multicellular organisms need to possess specialised cells that form tissues and organs to achieve this.
What are stem cells?
Undifferentiated (non-specialised) cells in the embryo that can differentiate to form any type of tissue.
What are the four main types of tissue in mammals?
Nervous, Connective, Muscular and Epithelial.
What is a connective tissue?
These support, connect or separate the different types of tissues and organs of the body. Cells are contained within extracellular fluid or matrix and may be surrounded by elastic or collagenous fibres. Eg: Tendons and Blood.
What is muscle tissue (3 types)?
- Skeletal - has bands of long cells of fibres giving powerful contraction and is used for locomotion in mammals.
- Smooth - has individual spindle-shaped cells which contract rhythmically but are not powerful so they are found in the walls of blood vessels and digestive/respiratory tracts.
- Cardiac - these have stripes but lack long fibres. They contract rhythmically with some force but do not tire easily.
What is epithelial tissue?
Covers and lines the body; eg: lining the intestines and trachea and covers our body as part of our skin. All epithelial cells sit on a basement membrane.
What are the 3 types of epithelial tissue?
Cuboidal, Ciliated columnar and squamous.
Describe all three types of epithelial tissue and state where each is found (3).
Cuboidal = Cube shape and tissue is one cell thick. Tissue is found in lining kidney tubules and ducts of glands.
Columnar = Rectangular shape and may have cilia present. Found in lining of tracheaa.
Squamous = Flattened cells. Found in alveoli and lining arteries.
Give two examples of organ systems and state 3 parts of each.
Digestive System (Stomach, Ileum and Colon)
Circulatory System (Heart, arteries, capillaries and veins)
