1.2 Flashcards
What is the typical size of an eukaryotic cell
30 micrometers um
What is a eukaryotic cell
Cells contains DNA in chromosomes in a nucleus and possess membrane-bound organelles
Size of mitochondria
1-10 micrometers um
Function of mitochondria
Site of aerobic respiration, producing ATP
Where is mitochondria present
All cells
Higher number in metabolically active cells eg muscles and liver
Chloroplast function
Site of aerobic respiration
Contain chlorophyll
Function of the nucleus
Contains DNA which codes for protein synthesis
Nucleus structure
- largest organelle in cytoplasm
- 10-20 um
- double membrane- outer is continuous with the rough endoplasmic reticulum
Nucleolus function
Produces rRNA/ribosomes
Nucleolus structure
Small spherical structure
Nuclear envelope function
Separates DNA from rest of the cell
Nuclear envelope structure
Double membrane with a space inbetween
Nuclear pore function
Allows movement of ribosomes out of the nucleus
Nuclear pore structure
The space in between the nuclear envelope
Nucleoplasm function
Contains chromatin which condenses to form chromosomes during cell division
Nucleoplasm structure
Material inside the nucleus
Function of mitochondria
Site of aerobic respiration
ATP synthesis
Mitochondria structure
- cylindrical shape - easier for Oxygen to diffuse
- self- replicating due to ribosomes and loops of DNA
- inner membrane folded to cristae - increase surface area for enzyme attachment during respiration
- matrix which contains 70s ribosomes and circle of DNA
Where is mitochondria present
All cells but in higher number in metabolically active cells eg muscle, liver and sperm cells
Chloroplast function
Site of photosynthesis and contains chlorophyll
Chloroplast structure
- self-replicating due to 70s ribosomes and circular DNA
- thylakoid increases surface area to absorb sunlight
- stroma contains 70s ribosomes and circle of DNA
- plant cells only
- granum which is stacks of thylakoids
Similarities between mitochondria and chloroplasts
- found in cytoplasm
- double membrane
- contain DNA
- folded internal membrane
- 70s ribosomes
- self-replicating
Differences between mitochondria and chloroplasts
- M animal and plant/Ch plant only
- M aerobic respiration and ATP synthesis/ Ch photosynthesis and contains chlorophyll
- M cristae/ Ch thylakoid
Function of both endoplasmic reticulums
Extensive transport system which is involved in the collection, storage and distribution of molecules
Rough endoplasmic reticulum function
Protein synthesis and transport
Endoplasmic reticulum structure
- complex system of double membrane
* continuous with the nuclear membrane
Rough endoplasmic reticulum structure
- ribosomes attached to surface
* parallel double membrane
Function of smooth endoplasmic reticulum
Lipid synthesis
Smooth endoplasmic reticulum structure
Membrane not parallel
No ribosomes
Ribosomes function
Protein synthesis and translation
Ribosomes structure
- chemical components - rRNA and protein
- small sub unit - mRNA attachment site
- large sub unit - tRNA attachment site
- in cytoplasm and attached to the rough endoplasmic reticulum
Golgi body function
- modification and packages proteins into vesicles for export
- transport and storage of lipids
- produces glycoproteins and lysosomes
Golgi body structure
Stacks of flattened sacks
How is the Golgi body formed
- small vesicles containing polypeptides are pinched off from the rough endoplasmic reticulum
- number of vesicles fuse to make a Golgi body
How does the Golgi body send materials to the cell membrane
- small vesicles pinched off from the Golgi body
- chemicals/materials in the secretory vesicles can be secreted when the vesicle moves to the cell membrane for exocytosis
Lysosomes function
• digest worn out organelles within the cell and foreign material that has been engulfed by phagocytosis
Lysosomes structure
- small, single membrane-bound vacuoles that are pinched off the Golgi body
- contain the digestive enzyme lysozyme
Centrioles function
- during cell division- they migrate to separate poles of the cell and produce spindle fibres
- this assists the movement of chromosomes
Centrioles structure
- two rings of microtubules at right angles to each other
- in animal cells and protoctistans
- absent from higher plant cells
Vacuole function
- supporting soft plant tissues
* store chemicals such as glucose and amino acids in the cell saps
Vacuole structure
- large central vacuole surrounded by the tonoplast
* plant cells only
Cell walls function
- provides strength to cell wall - resists expansion of vacuole
- transport of water and dissolved molecules and ions through gaps in cellulose fibres - apoplast pathway
Plasmodesmata function
- communication between cells via pores in the cell walls
- cytoplasmic bridges to facilitate efficient exchange of signalling molecules between neighbouring cells
- establishes living bridges between cells
Plasmodesmata structure
- plant cells only
* plasma membrane, cytoplasmic sleeve, desmotubule
What is a prokaryotic cell
Single-celled organism lacking membrane-bound organelles
What does the cell theory state
New cells are formed from other existing cells and that the cell is a fundamental unit of structure, function and organisation in all living organisms
What is different about prokaryotic cells and eukaryotic cells
- lack of membrane-bound organelles
- no nucleus loops of DNA
- 70s ribosomes not 80s
- murein cell wall
- mesosome for aerobic respiration
