3.4 Eukaryotic cell structure Flashcards
What are the distinguishing features of eukaryotic cells
- Cytoplasm containing membrane bound organelles
- DNA is enclosed in a nucleus
Name the organelles that are in both animal and plant cells(7)
Cell surface membrane
Mitochondrion
Nucleus
Ribosomes
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
golgi apparatus
What are the organelles specific to plant cells (3)
Chloroplasts-in plants and algae
Cell wall-in plants algae and fungi
Cell vacuole- only in plants
Describe the structure of the cell surface membrane (3)
- Hydrophilic phosphate heads-points to/ are attracted to water
- Hydrophobic fatty acid tails-point away/repelled from water
- Forms a phospholipid bilayer
Describe the function of the cell surface membrane
Selectively permeable-enables control of passage of substances in/out of cell
Receptors on surface which allows cell recognition/signalling
Describe the structure of nucleus (5)
- Has a nuclear envelope which is a double membrane
- Nuclear pores
- Nucleoplasm-Granular jelly like material
- Nucleolus-Smaller sphere inside which is the site of rRNA production and makes ribosomes
- Chromosomes- protein bound linear dna
What is a double membrane
- Controls what goes in and out of the nucelus and reactions take place in here
- The double membrane also surrounds the nucleus
Function of Nuclear pores
Allows the passage of large molecules such as mRNA out of the nucleus they are 40-100nm in diameter
What is the nuceloplasm
Jelly like material that makes up the bulk of the nucleus
Describe the function of the nucleus (4)
Holds/stores the 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 the structure of RER
Has lots of ribosomes-RER
Made of a system of membranes called cisternae
Describe the function of RER (3)
- Ribosomes are on the surface synthesising proteins
- Proteins processed/folded/transported inside RER
- Proteins packaged into Vesicles for transport e.g. to golgi appartus
Describe the structure of the SER
Lacks ribosomes on its surface and is more tubular in appearance
Made up of cisternae
Describe the function of the SER
- Synthesises and processes lipids e.g. cholesterol and steroid hormones
- Synthesises lipids stores and transports lipids and carbhohydrates
Describe the strcuture of a ribosome
- Made of ribosomal RNA
- Protein not a membrane bound organelle
describe the function of a ribosome
Site of protein synthesis(translation)
What is the difference between 80s and 70s ribosomes
80s-Found in euk is arouond 25nm in diameter
70s-Found in prok smaller than 80s
Describe the structure of golgi apparatus and golgi vesicles
Golgi A is flattened membrane sacs
Golgi V are small membrane sacs
Describe the fucntion of golgi A (4)
- Modifies proteins e.g. adds carbohydrates to produce glycoproteins
- Modifies lipids e.g. adds carbohydrates to glycolipids
- Packages proteins/lipids into the vesicles
- Produces lysosomes (a type of golgi Vesicle
transports modifies and stores lipids
What is the function of Golgi V
Transports proteins/lipids to desired location e.g. moves to and fuses with cell surface membrane
Describe the structure of lysosomes
Has a cell surface membrane and hydrolytci enzymes
Describe the function of lysosomes
- To release hydrolytic enzymes(lysozymes)
- To break down/hydrolye pathogens or worn out components
Describe the strcucture of mitochondria (3)
- Has a double membrane- controls the entry and exit of matierals
- Cristae-extensions of the inner membrane-provides a large surface area for the attatchment of enzymes
- Matrix contains 70s ribosomes proteins and lipids and DNA
Describe the function of mitochondria
Site of areobic respiration
To produce ATP for energy release e.g. for protein synthesis/vesicle movement/active transport
Describe the structure of chloroplasts in plants and algae (6)
- Has a double membrane
- Has a stroma which contains thylakoid membrane
- Has 70s ribosomes
- Circular DNA
- Lamella-thlyakoid linking grana
- Grana-stacks of up to 100 disc like structures called thylakoids- inside the thylakoid is the pigment chlorphyll
grana is also where the first stage of phptosyntehsis takes place
Describe the function of chloroplasts in plants and algae
Absorbs light energy for photosynthesis
To produce organic substances e.g. carbohydrates/lipids
How are chloroplasts adapted to thier function (3)
- The granal membrane provides a large surface area for the attatchment of chlorophyll
- The fluid of the stroma possess all the enzymes needed to make sugars
- Chloroplasts contain DNA and 70s ribosomes so they can quickly manufacture the proteins needed for photosynthesis
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
Provides mechanical strength to cell so it prevents cell changing shape or bursting under pressure due to osmosis
Describe the structure of the vacuole in plants
Has a tonoplast membrane and contains cell sap
WHen talking about the cell sap talk about the contents in the cell sap
What is in cell sap (3)
-sugars, amino acids, waste substances-
Describe the function of the vacuole in plants
- Maintains turgor pressure in cell (stopping plant wilting)
- contains cell sap which stores sugars, amino acids pigments and any waste chemicals
Describe how eukaryotic cells are organised in complex multicellualr organisms
Tissue-Group of specialised cells with a similar structure working together to perform a specific function
Organ-aggregations of tissues performing specifc functions
Organ system-Group of organs working together to perform specific functions
