Cells/cell structure Flashcards
Differences between eukaryotic and prokaryotic cells
• Prokaryotic cells are far smaller
• Eukaryotic cells have a nucleus whereas prokaryotic cells do not.
• Prokaryotic cells have no membrane bound organelles.
• Prokaryotic cells have 70S ribosomes and eukaryotic have 80S
• Prokaryotic cells have an outer layer called a capsule for protection
• DNA in prokaryotic cells is circular & extra plasmids, whereas it is linear in eukaryotic cells
Similarities between prokaryotic and eukaryotic cells
• Both have cytoplasm
• Both have a cell membrane
ORGANELLE FLASHCARDS IN FOLDER
What are vesicles?
Sphere of phospholipid bilateral that transport substances from one part of the cell to another
What is the endosymbiotic theory?
Bacterium engulfed by a ‘host cell’ and evolved into the mitochondria and chloroplasts
Evidence of endosymbiotic theory
• Some organelles have double membranes (outer membrane may be vesicular in origin)
• Reproduction occurs in a fission-like process
• Has own DNA which is circular
• Have 70S ribosomes
What is a tissue?
Group of similar cells organised in a structural unit
What is an organ?
Group of different tissues that work together to perform a specific function
What is an organ system?
Group of different organs that work together to perform a specific function
Features of a virus
• Genetic material in the form of RNA
• Matrix
• Capsid
• Lipid envelope
• Attachment protein
What is the process of virus replication?
- Virus attaches to host cell via receptors on the host cell surface membrane
- Virus injects genetic material into host, used to synthesise viral proteins
- New virus particles assembled
- New viruses burst out of, and damage/destroy, host cell
What are the stages of the cell cycle, starting from the beginning of interphase?
• G1 - cellular contents duplicated
• S - Each of the 46 chromosomes duplicated
• G2 - cell ‘double checks’ duplicated chromosomes for error, making necessary repairs
• Mitosis
• Cytokinesis
What are the stages of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
What happens during prophase?
• longest phase
• chromosomes condense
• centrioles move to opposite poles of cell
• spindle fibres start to develop
• nuclear envelope disintegrates and nucleolus disappears
What happens during metaphase?
• Chromosomes attach to spindle fibres by their centromeres
• They line up at right angles along the equator of the cell
What happens during anaphase?
• Stage is very fast
• Centromeres divide into 2
• Spindle fibres shorten and pull chromatids to opposite poles of the cell
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What happens during telophase?
• Chromatids referred to as chromosomes again
• Chromosomes lengthen and uncoil
• Spindle disintegrates
• Nuclear envelope reforms and nucleolus reappears
What is the importance of cell division?
Growth
Repair/replacement
Reproduction
What is mitosis?
Nuclear division that produces two daughter nuclei that are genetically identical to each other and the parent nuclei
What are centrioles and what is their structure/function?
• Small hollow cylinders
• A centrosome = 2 centrioles
• Form network of fine fibres in the cytoplasm called the cytoskeleton
• Support cell’s shape
• Organises and moves organelles
What is the mitotic index?
The ratio of number of cells undergoing mitosis to the total number of cells
Stages of binary fission
- Cell replicates it’s DNA
- Cytoplasmic membrane elongates, separating DNA molecules
- Cross wall forms; membrane invaginates
- Cross wall forms completely
- Daughter cells formed
What is cell division in prokaryotic cells called?
Binary fission
How is cancer treated?
Killing rapidly dividing cells by blocking part of the cell cycle e.g DNA replication or metaphase
What is the problem with cancer treatment?
Can also interfere with the cell cycle of normal cells that also divide rapidly
What are plasma membranes formed from?
Phospholipids
What are the roles of membranes?
• Separating cell contents from the outside world.
• Separating cell components from cytoplasm.
• Cell recognition and signalling.
• Holding components for some metabolic pathways
• Regulating transport in/out
Can lipid soluble molecules travel through phospholipid bilayers?
Yes
Can water soluble molecules travel through phospholipid bilayers?
No
What are proteins that go all the way through the cell membrane called?
Intrinsic proteins
What are proteins embedded in the cell membrane called?
Extrinsic proteins
What are the two types of intrinsic protein?
Channel proteins
Carrier proteins
What is a glycoprotein?
Protein with a carbohydrate group attached
What is a glycolipid?
Lipid which has a carbohydrate attached
