Biology 2.1.4: The Ultrastructure Of Eukaryotic Cells Flashcards
what are eukaryotic cells + examples?
cells tat have membrae-bond organelles
examples:
animal, plant, fungal + protoctist cells
what is the structure of eukaryotic cells?
they have:
- a nucleus (surrounded by a nuclear envelope), nucleolus inside the nucleus cytoplasm
- a cytoskeleton
- a plasma membrane
- includes membrane bound organelles such as; mitochondria, Golgi apparatus and endoplasmic reticulum
- it has small vesicles, and ribosomes.
what are membrane bound organelles? and what are their function?
organelles within eukaryotic cells which are covered by a membrane.
this keeps each organelle separate from the cell so it is a discrete compartment.
what is the structure of a nucleus/nuclear envelope and nucleolus?
the nucleus is surrounded by a double membrane called the nuclear envelope, which have pores.
the nucleolus does not have a membrane and hold RNA.
what is the function of a nucleus/nuclear envelope and nucleolus?
- the nuclear envelope separates contents if the nucleus from the rest of the cell.
- the pores in the nuclear envelope allow RNA and other large substances to enter the nucleus from the cytoplasm.
- the nucleolus is where ribosomes are made.
- the nucleus holds genetic material, controls the cell and provides instructions for protein synthesis
what is the structure of the rough endoplasmic reticulum?
- it is a system of membranes, containing fluid-filled cavities (cisternae) that are continuous with the nuclear membrane.
- coated with ribosomes
what is the function of the rough endoplasmic reticulum?
- RER is the intercellular transport system: the cisternae form channels for transporting substances from one area of a cell to another
- it provides a large surface area for ribosomes, which assemble amino acids into proteins.
what is the structure of the soft endoplasmic reticulum?
- a system of membranes, contains fluid-filled cavities (cisternae)
- no ribosomes on the surface
what is the function of the smooth endoplasmic reticulum?
- SER contains enzymes that catalyse reactions involved with lipid metabolism such as: synthesis of cholesterol, synthesis of lipids needed by the cell, synthesis of steroid hormones.
- involved with absorption, synthesis and transportation of lipids from the gut.
what is the structure of the Golgi apparatus?
consist of a stack of membrane-bound flattened sacs.
secretory vesicles bring materials to and from the Golgi apparatus.
what is the function of the Golgi apparatus?
- proteins are modified + packaged into vesicles that are pinched off and then stored in a cell or moved to the plasma membrane.
what is the structure of mitochondria?
- may be spherical, rod shaped or branched and are 2-5um long
- surrounded by two membranes with a fluid-filled space between them. The inner membrane is highly folded into cristae.
- the inner part of the mitochondria is a fluid-filled matrix
what is function of mitochondria?
- the sight of ATP production during aerobic respiration
- self-replicating so more can be made is the cells energy needs are increasing
- abundant in cells where most metabolic activity takes place.
what is the structure of chloroplasts?
- large organelles around 4-10um long
- found only in plant cells or protoctists
- surrounded by a double-membrane or envelope.
- inner membrane is continuous with stacks of flattened membrane sacs (thylakoids) which contain chlorophyll
- each stack/pile of thylakoids is called granum, the fluid-filled matrix is called the stroma.
- chloroplasts contain loops of DNA and starch grains
what is the function of chloroplasts?
- the site of photosynthesis
- in the first stage of photosynthesis, chloroplasts trap energy to make ATP (occurs in grana)
- stage 2, hydrogen reduces CO2, using energy from ATP to make carbohydrates (occurs in stroma)
- chloroplasts are abundant in leaf cells.
what is the structure of the vacuole?
surrounded by a membrane called the tonoplast + contains fluid.
what is the function of the vacuole?
- only in plant cells
- filled with water and solutes to maintain cell stability, when its full it pushes against wall making the cell turgid.
- turgidity keeps plants supported
what is the structure of lysosomes?
- small bags formed from the Golgi apparatus, each surrounded by a single membrane.
- contain powerful hydrolytic (digestive) enzymes
- abundant in phagocytic cells such as neutophils and macrophages
what is the function of lysosomes?
- keep hydrolytic enzymes separated from the rest of the cell
- engulfs old cell organelles and foreign matter, digesting them and returning the components to the cell for reuse
what is the structure of cilia and undulipodia?
- these are protrusions from the cell and are surrounded by the cell surface membrane
- each contain microtubules
- formed from centrioles
what is the function of cilia and undulipodia?
- epithelial cells lining the airway have hundred of cilia and move the band of mucus
- one cilium will act as an antenna containing receptors allowing the cell the detect signals about the environment
- the only human cell containing undulipodia is a spermatozoon, undulipodia allows it to move.
