2.1 Cell Structure Flashcards
Define eukaryotic cell
Eukaryotic cell - has a nucleus and other membrane bound organelles
Define ultrastructure
The features that can be seen by using an electron microscope
Draw and label a diagram of a plant and Animal cell
Structure and function of nucleus
Nucleus:
• Contains genetic information in form DNA
DNA contains instructions to make proteins
• Controls cells activities -(DNA transcription)
• surrounded by nuclear envelope with nuclear pores
• contain chromatin and nucleus
Structure and function of nucleolus
•Area in the nucleus
• produces ribosomes
• composed of proteins and RNA
Structure and function of nuclear pores
• Nuclear envelope contains many pores
• allow substances to move between the nucleus and cytoplasm
Structure and function of the smooth endoplasmic reticulum
responsible for synthesis and processing lipids and carbohydrates
Structure and function of rough endoplasmic reticulum
• Surface covered with ribosomes
• responsible for synthesis + transport of proteins
• Folds and processes proteins made at ribosomes
Structure and function of Golgi apparatus
• Group of fluid-filled membrane- bound flattened sacs. (Cisternae)
• vesicles at edge
•modifies and packages proteins + lipids into vesicles
• makes lysosomes
Structure and function of ribosomes
• floats free in cytoplasm / attached to RER
• made up of proteins and RNA
• not surrounded by membrane
•site of protein synthesis
Structure bad function of mitochondria
• oval shaped
• double membrane
•inner membrane folded to form cristae
•site of aerobic respiration producing ATP
•a lot found in active cells requiring lots of energy
Structure and function of Lysosomes
• a round organelle surrounded by a membrane
• contains hydrolytic enzymes
• Breaks down waste material
↳ digest invading cells or breakdown worn out components of cell
Structure and function of chloroplasts
•flat structure found in plant cells
•double membrane
•membranes inside called thylakoid membranes
•thylakoid membranes stack forming grana
•grana linked together by lamellae
•site of photosynthesis
Structure and function of the plasma membrane/cell surface membrane
•inside membrane
• made of lipids and proteins
• regulates movement of substances in and out of the cell
• receptor molecules on it to allow hormone response
Structure and function of centrioles
• Composed of microtubules
• all animals cells, some plant
• 2 centrioles = centrosome
• separation of chromosomes during cell division
Structure and function of cell wall
•Rigid - holds shape
• made of cellulose carbohydrate
• A supports cell and plant as a whole
• acts as defense against pathogens
Structure and function of cilia
• hair like structures on surface membrane of some animal cells.
• Cross section 9+2 - 9 protein microtubules ring and 2 in centre
•Allow cilia to move
More substances along cell surface
Structure and function of flagellum
•like cilia but longer
• 9+2 arrangement
• microtubules contract flagellum moves
• propel cells forward
State differences and similarities between plant and animal cells
• both have nucleus, mitochondria, membrane etc
Any plants: chloroplasts, permanent vacuole
, cell wall
Outline the process of protein synthesis (step by step)
• proteins made at ribosomes
• DNA codes for proteins via mRNA
• RNA leaves nucleus through nuclear pores
• ribosomes on RER synthesise mRNA into proteins
• pass into cisternae and packaged into vesicles
• vesicles move to golgi apparatus using cytoskeleton
• proteins might undergo further processing
• may enter more vesicles to be transported around cell
•secretory vesicles carry proteins to cell membrane
•vesicles fuse with cell surface membrane releasing contents by exocytosis
What are the 3 components of the cytoskeleton?
• Microfilaments
• microtubules
• intermediate fibres
What is the structure of microfilaments?
Solid strands
Contractile fibres formed from protein actin
What is the function of microfilaments?
• Responsible for cell movement + contraction during cytokinesis
• Support + keep (in place) cells organelles

What is the structure of microtubules?
• Globular tubulin proteins polymerise to form tubes to form scaffold structure
What is the function of microtubules?
• Determine shape of cell + track movement of organelles
e.g. vesicles
What is the function of intermediate fibres?
Mechanical strength + help maintain integrity
What are the functions of the cytoskeleton in the cell?
Support
Strength
Shape
Movement
Describe the importance of the cytoskeleton in moving cilia/flagella
Pairs of parallel microtubules slide over one another in a beating motion
What is the arrangement of microtubules in cilia/flagella?
9 + 2 arrangement
2 central microtubules
9 pairs around
How is the cytoskeleton dynamic?
Constantly changing to respond to changes in the cell and carry out its function
What is the importance of the cytoskeleton for neutrophils?
•Cytoskeleton shapes and gives neutrophils behaviour
•neutrophils have multilobed nucleus and are very flexible
↳ can squeeze through small spaces to get to infection sites
Define prokaryotic cell
Cells with no membrane bound nucleus or organelles
Give examples of eukaryotic cells
Plant
Animal - human liver cell
Fungi
Give examples of prokaryotic cells
Bacteria - e coli
What is the structure and function of the cell wall in prokaryotic cells?
• Made of peptidoglycan/murein
•Maintains structure
What is the structure and function of ribosomes in prokaryotic cells?
• Small - 70s
• Protein synthesis
What is the structure and function of bacterial flagellum in prokaryotic cells
• Thinner, without 9+2
• rotates with whip like movement to propel cell along
What is the structure and function of the plasma membrane in prokaryotic cells?
• Controls entry/ exit of the cell
What is the structure and function of plasmid in prokaryotic cells?
• Rings of DNA in cytoplasma
What is the structure and function of Bacterial chromosomes in prokaryotic cells?
• Supercoiled - make it compact
• genes grouped into operons - turned on/ off together
What is the structure and function of Pili in prokaryotic cells?
• Adhesion organelles
-allow bacteria to colonise environmental surfaces /cells
+ resist flushing
What is the structure and function of Slime capsule in prokaryotic cells?
• Defense + moisture
Compare eukaryotic and prokaryotic cells : nucleus, DNA, organelles, cell wall, ribosomes, cytoskeleton, reproduction, cell type, cell surface membrane
Nucleus:
P- no E- present
DNA:
P- circular E- linear
Organelles:
P- non-membrane bound E- both with/out membranes
Cell wall:
P- murein E- cellulose (plant only)
Ribosomes:
P- 70s E- 80s
Cytoskeleton:
P- yes E- more complex
Reproduction:
P- binary fission E- asexual/sexual
Cell type:
P- unicellular E- multicellular
Cell surface membrane:
P- yes E- yes
What does the endosymbiotic theory state?
•Mitochonaria + chloroplasts were once bacteria cells
• theory - these prokaryotes were taken inside another cell as endosymbiont
↳ an organism that lives within the body/cells of another organism
