12.4 Studying Cells Flashcards
Define eukaryotic.
‘True nucleus’
DNA is enclosed by a nuclear membrane.
Have membrane bound organelles
e.g. animal cells
Which two organelles of an animal cell are the only ones visible under a light microscope?
Nucleus
Cell membrane
How are epithelial cells adapted for their role in absorption and secretion within the digestive system?
Cell membrane is folded into structures called microvilli which increase surface area for absorption.
Give the structure and function of the nucleus.
Structure:
- Largest organelle in the cell.
- Nuclear envelope= double membrane.
- Nuclear pores= allow passage of molecules such as mRNA, in and out of the nucleus.
- Nucleoplasm= granular, jelly-like material.
- Chromatin= unwound, uncondensed DNA, wrapped around histone proteins.
- Nucleolus= which is where the rRNA is made to form ribosomes.
Function:
- Site of DNA replication and transcription (making mRNA).
- Contains DNA for each cell to synthesise proteins to control cell activity.
Give the structure and function of the mitochondria.
Structure:
- Double membrane.
- Inner membrane is called the cristae.
- Fluid centre called the mitochondrial matrix.
- Prokaryotic, small, circular DNA and its own 70s ribosomes.
Function:
- Site of ATP production by aerobic respiration.
- DNA to code for the enzymes needed in respiration.
Give the structure and function of the rough endoplasmic reticulum.
Structure:
- Made from highly folded membranes with 80s ribosomes embedded.
- Membrane is folded into flattened sacks called cisternae.
- Joined to the nucleus.
Function:
- Synthesises and transports proteins throughout the cell.
Give the structure and function of the smooth endoplasmic reticulum.
Structure:
- Membrane is folded into flattened sacks called cisternae.
Function:
- Recombines glycerol and fatty acids to make triglycerides.
- Packages triglycerides into vesicles and transports them to the Golgi apparatus.
Give the structure and function of the ribosomes.
Structure:
- Small
- Made up of 2 rRNA subunits.
- Eukaryotic cells contain 80s ribosomes.
- Prokaryotic cells, mitochondria and chloroplast contain 70s ribosomes.
Function:
- Site of protein synthesis.
Give the structure and function of the Golgi apparatus and Golgi vesicles.
Structure:
- flattened sacs made of fluid-filled membranes pinch off smaller sacs called vesicles at their ends.
Function:
- Sorts, modifies and packages proteins and triglycerides into vesicles.
- Produce secretory enzymes.
- Form lysosomes.
- Add carbohydrates to proteins to form glycoproteins.
Give the structure and function of lysosomes.
Structure:
- Bags of digestive/hydrolytic enzymes.
- Bound by a single membrane with no internal structure.
Function:
- Hydrolyse damaged, phagocytic and dead cells.
- Digest worn-out organelles for reuse of materials.
- Completely break down dead cells (autolysis).
- Exocytosis- release enzymes to outside of cell to destroy material.
Give the structure and function of the cell surface membrane.
Structure:
- Phospholipid bilayer with molecules embedded within and attached on e.g. transport proteins, carbohydrates and cholesterol arranged in a fluid mosaic model.
Function:
- Controls passage of molecules in and out of the cell.
Give the structure and function of centrioles. (ANIMAL ONLY)
Structure:
- Form a network of spindle fibres across the cell onto which the chromosomes attach.
Function:
- Pull the chromosomes/chromatids apart during mitosis.
Give the structure of microvilli and how this speeds up absorption of digested food.
Structure:
- Finger-like projections of the cell membrane
Speeds up absorption by greatly increasing the surface area of the cell membrane.
Give the structure and function of the vacuole. (PLANT ONLY)
Structure:
- Filled with fluid surrounded by a single membrane called a tonoplast.
Function:
- Make cells turgid and therefore provide support.
- Temporary store of sugars and amino acids.
- Pigments may colour petals to attract pollinators.
Give the structure and function of chloroplasts. (PLANT ONLY)
Structure:
- Surrounded by a double membrane
- Contains thylakoids (folded membrane embedded with chlorophyll and ATP synthase enzyme to produce ATP), granum, stroma (fluid-filled part), and 70s ribosomes and prokaryotic DNA.
Function:
- Site of photosynthesis.