Topic 1:2 - prokaryotes/eukaryotes + organelles Flashcards
name and describe 6 features of a prokaryotic cell
- cell wall - maintains shape, provides rigidity and structural support
- capsule - external covering for protection and sticky adhesion
- flagella - fibrous projections that propel cell (movement)
- fimbrae - thin protein fibres that attach bacteria to surfaces and cells
- DNA - continuous, circular molecule of DNA located in the nucleoid
- plasmids - circular DNA molecules that are not part of the main chromosome
What are prokaryotes?
Single celled organisms, simple cells that are smaller than eukaryotic cells. e.g arches or bacteria
What are eukaryotes?
organisms whose cells have a membrane-bound nucleus and organelles. (often multicellular)
compare the organisation in eukaryotes vs prokaryotes
prokaryotes: unicellular
eukaryotes: can be unicellular but are often apart of a tissue in a multicellular organism
compare the DNA in eukaryotes vs prokaryotes
prokaryotes: circular DNA located in nucleoid
eukaryotes: multiple linear chromosomes located in the nucleus
compare the division between prokaryotic cells and eukaryotic cells
prokaryotic: binary fission
eukaryotic: mitosis and meiosis (and if single celled organism then mitosis & binary fission)
compare the size of eukaryotic and prokaryotic cells
prokaryotes: smaller cells 0.5-5.0 micrometers
eukaryotes: larger cells 1-100 micrometers
compare the organelles in eukaryotic and prokaryotic cells
prokaryotes: no membrane-bound organelles or nucleus
eukaryotes: contains membrane-bound organelles and nucleus
6 common features in eukaryotic and prokaryotic cells
- cell membrane
- ribosomes (site of protein synthesis)
- nucleic acids ( polymers of nucleotides)
- proteins (polymers of amino acids)
- cytoplasm/cytosol
- ATP (energy storage molecule)
describe the endoplasmic reticulum
cell type: all eukaryotic cells
an interconnected membrane system of hollow tubes and sacs. two types:
Rough ER: has ribosomes on the surface and is the site of protein synthesis
Smooth ER: has no ribosomes and is responsible for lipid synthesis
Describe vacuoles
cell type: all eukaryotic cells
function: storage of water, giving the cell shape and rigidity. plants have especially large vacuoles
describe the nucleus
cell type: all eukaryotic cells
function: location of the chromosomes. DNA replication and transcription occurs at the nucleus.
describe the nucleolus
cell type: all eukaryotic cells
location: inside the nucleus
function: site of ribosomal RNA (rRNA) synthesis
explain the importance of internally folded membranes
increases the exposed surface area available for biochemical processes to occur. This is because more enzymes are exposed to catalyse these reactions.
This increases the efficiency of the organelle
e.g: mitochondria, chloroplasts, ER, Golgi body
describe the cell wall
cell types: plants and fungi
function: provides structure, support and protection. In plants it is composed of cellulose, in fungi it is composed of chitin
describe the Golgi body
cell type: all eukaryotic cells
function: modifies proteins and lipids before packaging into vesicles which are transported to other parts of the cell or to the cell membrane for excretion.
describe the mitochondria
cell type: all eukaryotic cells
function: site of later stages or aerobic respiration. contains small circles of DNA and ribosomes
describe lysosomes
cell type: animal (some plant)
function: vesicles containing digestive enzymes that digest old organelles, storage molecules and whole cells. (e.g neutrophils - white blood cells that engulf and digest pathogens)
describe the cytoskeleton
cell type: all eukaryotic cells
function: a network of long protein fibres that support the structure and shape of the cell. Involved in positioning/moving organelles around the cell. Has a role in transporting substances and also in cell division (spindle fibre synthesis).
describe chloroplasts
cell type: plants
function: to absorb light. site of photosynthesis. contains small circles of DNA and ribosomes
