Structure and function of eukaryotic organelles Flashcards
Structure of nucleus
- large structure
- contains chromatin (forms chromosomes)
- contains nucleolus and nuclear envelope
Function of nucleus
controls metabolic activities and contain genetic material
Structure of nuclear envelope
- double membrane
- nuclear pores for tRNA + genetic information to pass
- genetic information (DNA is stored here)
Function of the nuclear envelope
- allows tRNA molecules with genetic information to pass through for protein synthesis, outside the nucleus in the ribosomes
Structure of nucleolus
- within the nucleus
- made up of proteins and RNA
- takes up around 25% of the volume of the nucleus
Function of nucleolus
- responsible for the production of ribosomes
- ribosomal RNA is produced, which combines with ribosomes necessary for protein synthesis
Structure of rough endoplasmic reticulum
- contains many ribosomes
- THINK - ribosomes = rough
- made of tubules, vesicles and cisternae
- cisternae = flattened membrane discs (involved in modification of proteins)
Functions of rough endoplasmic reticulum
- responsible for the synthesis and transportation of proteins
- THINK - ribosomes = PROTEIN synthesis
Structure of smooth endoplasmic reticulum
- contains no ribosomes
- a network of tube-like structures that have a large surface area for storage of key enzymes
- connected to the outer membrane of the nucleus
Function of smooth endoplasmic reticulum
- stores and synthesises lipids
- stores and synthesises carbohydrates
Structure of golgi apparatus
- similar to endoplasmic reticulum
- compact structure of cisternae
- does not contain ribosomes
Function of golgi apparatus
- modifies proteins and ‘packages’ then into vesicles
- if staying in the cells, its for be lysosomes
- if leaving the cell, its for secretory vesicles
Structure of a ribosome
- free floating in cytoplasm / attached to rough endoplasmic reticulum
- no membrane
- made of RNA molecules, constructed in nucleus
Function of ribosome
- translates tRNA into a long string of amino acids, during protein synthesis
- site of protein synthesis
Structure of mitochondria
- double membrane
- inner membrane folded into cristae (contains enzymes for aerobic respiration)
- fluid interior = matrix (contains ribosomes and mitochondrial DNA - mtDNA)
- can reproduce own enzymes and themselves
Function of mitochondria
- site of final stages of cellular respiration (energy stored in bonds of complex
- organic molecule ATP made available for cell to use
Structure of vesicles
- membranous sacs with single membrane and fluid inside
Function of vesicles
- transport materials inside the cell
Structure of lysosomes
- special form of vesicles
- contain hydrolytic enzymes
Function of lysosomes
- breaking down waste materials in the cell
- immune system = break down pathogens ingested by phagocytic cells
- important role in apoptosis or cell death
Structure of centrioles
- component of cytoskeleton
- composed of microtubules
- in most eukaryotic cells, not flowering plants and most fungi
- centrosome = 2 associated centrioles responsible for assembly and organisation of spindle fibres in cell division
Function of centrioles
- gives cells shape and stability
- responsible for cell movement and movement of organelles within the cell
Structure of cilia
- two central microtubules surrounded by 9 pairs of microtubules like a wheel in “9+2” arrangement
- pairs of parallel microtubules slide over each other = move in beating motion
- on the surface of cells
Function of cilia
- mobile / stationary
- stationary = important role in sensory organs e.g. nose
- mobile cilia = beat in rhythmic manor - move fluid + objects e.g. woft egg through fallopian tubes, towards uterus or mucus away from lungs
Structure of plasma membrane
- embedded with proteins and cholesterol
- plasma membrane composed of phospholipid bilayer
Function of the plasma membrane
- protect cell from surroundings
- regulates movement of substances in and out of the cell
Name the 3 structures within the cytoskeleton
- microtubules
- microfilaments
- intermediate fibres (composed of fibres)
Structure and function of microtubules
- scaffold-like structures determines cells shape
- globular tubular proteins polymerise to form tubes
- acts a track for movement of organelles
- spindle fibres controlled by these
Structure and function of microfilaments
- contractile fibres formed from protein, actin
- responsible: cell movement + cell contraction during cytokinesis
Structure and function of intermediate fibres
- gives mechanical strength to cells, to maintain integrity
Structure of flagella
- much longer than cilia but fewer in number
- hair-like extensions that extend past some cell types
Function of flagella
- enable cell motility
- sometimes used as cell organelle - detects chemical changes in cells environment
Structure of chloroplasts
- found in all green parts of cell (not roots)
- contain DNA and ribosomes
- double membrane structure (stroma)
- network of membranes = flattened sacs (thylakoids) stacked together form granum.
- grana joined by membranes (lallae)
- grana contain chlorophyll pigments
Function of chloroplasts
- site of photosynthesis
- internal membrane: large surface area for enzymes, proteins and pigment molecules for photosynthesis
Structure of cell wall
- made of complex carbohydrate (cellulose)
- freely permeable
- surrounds cell-surface membrane
Function of cell wall
- gives cells shape keeps cell rigid due to components of cell pressing against it
- substances can pass through (freely permeable)
- defence mechanism - blocks out pathogens + any other foreign substances
