2.1 Cell structure

What are the distinguishing features of eukaryotic cells?

• Cytoplasm containing membrane-bound organelles.

• DNA enclosed in a nucleus.

Which other cell types are similar to plant cells?

• Algal and fungal cells are similar to plant cells.

What are the functions of the cell-surface membrane?

• Selectively permeable, enabling control of passage of substances in and out of cell.

• Molecules, receptors, or antigens on surface allow cell recognition and signalling.

What are the main structural features of the nucleus?

• Nuclear envelope with double membrane and nuclear pores.

• Nucleoplasm.

• Nucleolus.

• Histone-bound, linear DNA existing as chromatin or chromosomes.

What type of membrane surrounds the nucleus?

• Double membrane.

What structures are found in the nuclear envelope?

• Nuclear pores.

What is the material inside the nucleus called?

• Nucleoplasm.

What is the dense region within the nucleus called?

• Nucleolus.

What are the two forms of DNA in the nucleus?

• Chromatin, which is condensed.

• Chromosome, which is highly condensed.

What proteins is DNA bound to in the nucleus?

• Protein or histone-bound, linear DNA.

What are the functions of the nucleus?

• Holds genetic information which codes for amino acid sequences of polypeptides.

• Site of DNA replication.

• Site of transcription, producing mRNA.

• Nucleolus makes ribosomes or rRNA.

What are the main structural features of a ribosome?

• Made of ribosomal RNA and protein with two subunits.

• Not a membrane-bound organelle.

What is the function of a ribosome?

• Site of protein synthesis or translation.

What are the main structural features of rough and smooth endoplasmic reticulum?

• Ribosomes on rough ER.

• System of membranes.

What is found on the surface of rough endoplasmic reticulum?

• Ribosomes on surface.

What are the functions of rough endoplasmic reticulum?

• Ribosomes on surface synthesise proteins during translation.

• Proteins processed, folded, and transported inside rER.

• Proteins packaged into vesicles for transport, for example to Golgi apparatus.

What are the functions of smooth endoplasmic reticulum?

• Synthesises, processes, transports, and packages lipids and carbohydrates.

• For example, cholesterol and steroid hormones.

What are the main structural features of the Golgi apparatus and vesicles?

• Golgi apparatus: flattened membrane sacs.

• Golgi vesicle: small membrane sac.

What is the structure of the Golgi apparatus?

• Flattened membrane sacs.

What is the structure of a Golgi vesicle?

• Small membrane sac.

What are the functions of the Golgi apparatus?

• Modifies protein, for example adds carbohydrates to produce glycoproteins.

• Modifies lipids, for example adds carbohydrates to make glycolipids.

• Packages proteins and lipids into Golgi vesicles.

• Produces lysosomes, a type of Golgi vesicle.

What are the functions of Golgi vesicles?

• Transports proteins and lipids to their required destination.

• For example, moves to and fuses with cell-surface membrane.

What are the main structural features of a lysosome?

• Membrane.

• Hydrolytic enzymes.

What are the functions of lysosomes?

• Release hydrolytic enzymes, for example lysozymes.

• To break down or hydrolyse pathogens or worn-out cell components.

What are the main structural features of mitochondria?

• Outer membrane.

• Cristae, the inner membrane folds.

• Matrix containing small 70S ribosomes and circular DNA.

What is the outermost part of a mitochondrion?

• Outer membrane.
  

What are the inner membrane folds called?

• Cristae.
  

What is the name of the fluid inside mitochondria?

• Matrix.

What is found in the matrix?

• Small 70S ribosomes.

• Circular DNA.

What are the functions of mitochondria?

• Site of aerobic respiration.

• To produce ATP for energy release from respiratory substrates.

• For example, for protein synthesis, vesicle movement, or active transport.

What are the main structural features of chloroplasts?

• Double membrane.

• Stroma containing thylakoid membrane, small or 70S ribosomes, circular DNA, and starch granules or lipid droplets.

• Grana, which are stacks of thylakoid.

• Lamella, which are thylakoids linking grana.

What surrounds the chloroplast?

• Double membrane.

What is the fluid inside chloroplasts called?

• Stroma.

What is found in the stroma?

• Thylakoid membrane.

• Small or 70S ribosomes.

• Circular DNA.

• Starch granules or lipid droplets.

What are grana?

• Stacks of thylakoid.

What are lamella?

• Thylakoids linking grana.

What are the functions of chloroplasts?

• Pigments such as chlorophyll absorb light energy for photosynthesis.

• To produce organic substances such as carbohydrates or lipids.

What are the main structural features of the cell wall in plants, algae and fungi?

• Composed mainly of cellulose in plants and algae.

• Composed of chitin in fungi.

What is the cell wall of plants and algae composed of?

• Composed mainly of cellulose, a polysaccharide.

What is the cell wall of fungi composed of?

• Composed of chitin, a nitrogen-containing polysaccharide.

What are the functions of the cell wall?

• Provides mechanical strength to cell.

• Prevents cell changing shape or bursting under pressure due to osmosis.

What are the main structural features of the plant cell vacuole?

• Tonoplast membrane.

• Cell sap.

What is the membrane surrounding the plant vacuole called?

• Tonoplast membrane.

What is the fluid inside the plant vacuole called?

• Cell sap.

What are the functions of the plant cell vacuole?

• Maintains turgor pressure in cell, stopping plant wilting.

• Contains cell sap, storing sugars, amino acids, pigments, and any waste chemicals.

How are eukaryotic cells organised in complex multicellular organisms?

• Cells become specialised for specific functions.

What is a tissue?

• Group of specialised cells with a similar structure working together to perform a specific function, often with the same origin.

What is an organ?

• Aggregations of tissues performing specific functions.

What is an organ system?

• Group of organs working together to perform specific functions.