1.2 cell structure and organisation Flashcards
Define eukaryotic cell
A type of cell that contains a true nucleus
along with membrane-bound organelles.
Describe the structure of the nucleus.
● Surrounded by nuclear envelope which is
semi-permeable and double membraned
● Nuclear pores allow substances to enter/exit
● Dense nucleolus (made of RNA and proteins) assembles ribosomes
Describe the function of the nucleus.
● Contains DNA coiled around chromatin into
chromosomes
● Coordinates cellular activities
What is chromatin?
A DNA-protein complex found in
eukaryotic cells.
Describe the structure of mitochondria.
● Surrounded by double membrane, mitochondrial envelope
● Folded inner membrane forms cristae (large surface area)
● Fluid matrix contains mitochondrial DNA, respiratory enzymes, lipids and proteins
Describe the function of mitochondria
Site of aerobic respiration to produce ATP
Describe the structure of the endoplasmic reticulum (ER).
● Series of flattened membrane-bound sacs
(cisternae) within the cytoplasm, continuous with the nuclear envelope
● Two types: rough ER and smooth ER
Describe the function of the smooth
endoplasmic reticulum (SER).
lipid synthesis
Describe the function of the rough endoplasmic reticulum (RER)
Many ribosomes attached for protein
synthesis and transport
Describe the structure of ribosomes.
● Made from rRNA and proteins
● Found free in the cytoplasm or
associated with the RER
Describe the function of ribosomes
Site of protein synthesis (translation)
● Large subunit joins amino acids
● Small subunit reads RNA
Describe the structure of the Golgi body.
● Planar stack of membrane-bound, flattened sacs
● Cis face aligns with RER
● Molecules are processed in cisternae
● Vesicles leave via trans face by exocytosis
Describe the function of the Golgi apparatus
● Modifies and packages proteins for export
● Synthesises glycoproteins
Describe the structure and function of
lysosomes
● Fluid-filled vesicles surrounded by a single
membrane, contain enzymes
● Role in phagocytosis,
contains digestive enzymes that break down macromolecules
Describe the structure of centrioles.
● Cylindrical structure
● Organised into microtubules in a 9+0 pattern
● Found in pairs in centrosomes
Describe the function of centrioles
● Migrate to opposite poles of the cell during
prophase
● Involved in the organisation of spindle fibres
Describe the structure of a chloroplast.
● Disk shaped surrounded by double membrane
● Thylakoids - flattened discs stacked to form grana
● Grana - contain photosystems with chlorophyll
● Intergranal lamellae - tubes attach thylakoids in adjacent grana
● Stroma - fluid-filled matrix