Cells Flashcards
what is the structure of the nucleus?
- has a double membrane, the nuclear envelope which contains pores which allows substances like RNA through
- nucleolus does not have a membrane, it contains RNA
- contains chromatin, DNA wound around histone proteins. the chromatin is the nucleoplasm
what is the function of the nucleus?
- site of DNA replication and transcription
- nuclear envelope separates the contents of the nucleus from the rest of the cell
- contains nearly all of the genetic material, contains instructions for making proteins/genetic code
- RNA can leave nucleus through pores in nuclear envelope
- nucleolus is where ribosomes are made
- chromosomes contain organisms genes
what is the structure of mitochondria?
- 2.5um long
-double membrane
-inner membrane is folded into a cristae
-middle space between membranes is filled with fluid called the matrix
what is the function of mitochondria?
- site of ATP production during aerobic respiration
- have own DNA, ribosomes so can create enzymes for respiration inside organelle
- abundant in cells where much metabolic energy is needed
what is the structure of chloroplasts?
- large organelles
- only in plant cells
- double membrane
- contain stacks of flattened membrane sacs called thylakoids which contain chlorophyll, each stack of thylakoids is called a grana
- contains the liquid called stoma which contains enzymes, lipids, starch, ribosomes, loops of DNA
what is the function of chloroplasts?
- site of photosynthesis
- light energy I strapped by chlorophyll and used to make ATP this occurs in the grana
- uses energy from ATP to make carbohydrates occurs in stoma
- chloroplasts are abundant in leaf cells particularly the palisade mesophyll layer
what is the structure of the rough endoplasmic reticulum?
- network of membranes formed of flattened sheet like sacs called cisternae
- coated with ribosomes
- appears as pairs of parallel lines running through cytoplasm
what is the function of rough endoplasmic reticulum?
- intracellular transport system: the cisternae form channels for transporting substances
- provides a large surface area for ribosomes to make amino acids into proteins
- transports and modifies ribosomes
what is the structure of the smooth endoplasmic reticulum?
- system of folded membranes called cisternae
- no ribosomes
what is the function of the smooth endoplasmic reticulum?
- contains enzymes involved in lipid synthesis
- transport and absorption of lipids
what is the structure of the Golgi apparatus?
- stack of membrane bound flattened sacs making cisternae
- secretary vesicles pinch off from the cisternae
what is the function of the Golgi apparatus?
- modifies proteins for example:
adding sugar molecule to make glycoproteins and being folded into their 3D shape - transports proteins by pinching them of in vesicles
- form lysosomes
what is structure of a lysosomes?
- formed from golgi apparatus
- single membrane
- contain hydrolytic digestive enzymes
what is the function of lysosomes?
- engulf old cell organelles
- exocytosis
what is the structure of cilia?
- hairlike projections out of cells
- contains microtubules
- formed from centrioles
what is the function of cilia?
- waft substances
- detect signals
what is the structure of vacuole?
- surrounded by membrane called tonoplast
- contains fluid
what is the function of vacuole?
- maintains cell stability
- makes cell turgid
what is the structure of centrioles?
- 2 bundles of microtubules at right angles
- microtubules are made of tubulin
- occur in pairs to form a centrosome
what is the function of centrioles?
- involved in the production of spindle fibres
- involved in formation of cilia
what is the structure of cytoskeleton?
- a network of fibres within cytoplasm
- consists of microfilaments, microtubules and intermediate fibres
- cytoskeletal motor proteins, allows hydrolysis of ATP to produce energy
what is the structure of ribosomes?
- small
- made of 2 sub units of protein and RNA
- 80s found in eukaryotic cells
- 70s found in mitochondria, chloroplasts and prokaryotic cells
what is the function of ribosomes?
- protein synthesis
what is the structure of the cell wall?
- plant: made of bundles cellulose fibres
- fungi: made of chitin
what is the function of the cell wall?
- prevents cell bursting, keep cell turgid
- prevent strength and support
- maintain cell shape
- permeable
what is the magnification of a light microscope?
X1500
what is the resolution of a light microscope?
0.2um
what is the magnification of a SEM?
x200,000
what is the resolution of a SEM?
1 nm
what is the magnification of a TEM?
x million
how are proteins made and secreted?
- gene contain instructions which are transcribed into length of RNA called mRNA
- many copies of the mRNA are made and pass out of nuclear envelope to the ribosomes
- at ribosomes the instructions are translated and protein molecules are assembled
- pass into RER
- vesicles from RER to Golgi apparatus
- vesicles fuse to Golgi apparatus where it is modified
- vesicles pass to plasma membrane
- Vesicle and plasma membrane fuse and protein is released
