Cells Flashcards
Distinguishing feature of euk
Cytoplasm containing membrane bound organelles
So dna enclosed in nuclies
Nucleus structure
Nuclear envelope double membrane and has nuclear pores
Nucleoplasm
Protein histone bound dna
Chromatin condensed
Chromosome highly condensed
Nucleus functions
● Holds / stores genetic information which codes for polypeptides (proteins)
● Site of DNA replication
● Site of transcription (part of protein synthesis), producing mRNA
● Nucleolus makes ribosomes / rRNA
Describe ribosome structure and functiom
Made of ribosomal rna and protein
Not membrane bound
Site of protein synthesis
Rer
● Ribosomes on surface synthesise proteins
● Proteins processed / folded / transported inside rER
● Proteins packaged into vesicles for transport eg. to Golgi apparatus
Ser
Synthesis and process lipids
Golgi apparatus
● Modifies protein, eg. adds carbohydrates to produce glycoproteins
● Modifies lipids, eg. adds carbohydrates to make glycolipids
● Packages proteins / lipids into Golgi vesicles
● Produces lysosomes (a type of Golgi vesicle)
Golgi vescile
Transports proteins / lipids to their required destination
● Eg. moves to and fuses with cell-surface membrane
Mitochondria
Outer membrane
Cristae inner folds
Matrix containing 70S ribo and circular dna
● Site of aerobic respiration
● To produce ATP for energy release
Chloroplasts
Double membrane
Stroma containing thylakoid membrane
70s ribosomes
Circular dna and starch droplets
Lamella thylakoid linking grana
Grana stacks of thylakoids
Absorb light energy for photosynthesis to produce organic substances
Describe the structure of the cell wall in plants, algae and fungi
● Composed mainly of cellulose (a polysaccharide) in plants / algae
● Composed of chitin (a nitrogen-containing polysaccharide) in fungi
Describe the function of the cell wall in plants, algae and fungi
Mechanical strength
● So prevents cell changing shape or bursting under pressure due to osmosis
Cell vacuole
Tonoplast membrane
Cell sap
● Maintains turgor pressure in cell (stopping plant wilting)
● Contains cell sap → stores sugars, amino acids, pigments and any waste chemicals
Tissue
Group of specialised cells with a similar structure working together to perform a specific function, often with the same origin
What are the distinguishing features of prokaryotic cells?
● Cytoplasm lacking membrane-bound organelles
● So genetic material not enclosed in a nucleus
Prok structure
Capsule plasmid and flagella sometimes
Cell wall cytoplasm ribosomes circular dna and cell walls always
