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Description
Flashcards by Megan Ching, updated more than 1 year ago
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Created by Megan Ching
almost 7 years ago
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| Question | Answer |
| 3 tenets of cell theory: | 1. The cell is the smallest unit of life and it is the basic unit of structure and organisation in an organism. ▪All cells are capable of maintaining its own metabolic activity. 2. All cells come from pre-existing cells. ▪Each cell has its own hereditary materials that are passed down from parent to daughter cells. 3. All living organisms are composed of cells. ▪ Organisms that are made up of one cell are unicellular and those made up of many cells are multicellular. |
| what unit of measurement is used for whole cells/large cell structures eg chlroplast/nucleus and smaller cell structures (ultrastructures) eg ribosomes and large organic molecules (proteins/lipids) | micrometer and nanometer respectively |
| units of measurement: | |
| formula for magnification | Image size / Actual size |
| A type of prokaryote | Bacteria |
| A type of Eukaryote | Animal and plant cells |
| Characteristics of prokaryotic cells | 1. DNA is not enclosed by nuclear membrane 2. DNA located in nucleoid (distiguishing feature) 3. DNA not complexed with histones 4. Do not have membrane-bound organelles |
| Shape and Size of prokaryotic cell | Shape: wide diversity Size: small; 0.5-5.0mm in length; unicellular |
| Structure and Function of Cell Wall | S: composed of peptidoglycan F: ▪ Gives the cell shape ▪ Prevents rupture ▪ Serves as an anchorage point for flagella |
| Structure and Function of Capsule | S: sticky layer of polysaccharide or protein F: ▪Enable bacteria to adhere to their substrate or each other to form a colony ▪ Offer protection against dehydration and sheild pathogenic bacteria from attacks by their host's immune system. |
| Structure and Function of Pili aka Frimbriae | S: Hair-like protein appendages aka attachment /adhesion pili F: Enable bacteria to stick to their substrate eg teeth or to one another. |
| Structure and Function of Sex Pili | S: longer but less in numbers as compared to attachment pili F: Are appendages that pull 2 bacteria cells together prior DNA transfer from one cell to another via conjugation |
| Flagellum | One or many can be present Function: Responsible for motility of the bacteria |
| Function of Plasma Membrane | May form in-foldings which carry out specialised functions like ATP production via mesosomes and photosynthesis (only for cyanobacteria) |
| How do prokaryotic cells perform photosynthesis and respiration without chloroplast mitochondria? | Plasma Membrane |
| what type of ribosomes do prokaryotic cells have? | 70S Ribosomes |
| Structure of 70S ribosomes | S: made up of 2 ribosomal subunits - one small ribosomal subunit (30S) and one large ribosomal subunit (50S) Smaller than 80S ribosomes |
| Structure of Bacterial chromosome | 1. Single chromosome 2. Circular double stranded 3. Located in nucleoid 4. DNA not complexed with histones |
| Structure of plasmids | 1. Extra-chromosomal DNA 2. Small, circular and double stranded DNA which replicates independently of the bacterial chromosome 3. One or several plasmids might be present. |
| Structure of prokaryotic cell | 1. Cell wall 2. Capsule 3. Pili 4. Sex pili 5. Flagellum 6. Lack of membrane-bound organelles 7. Plasma membrane 8. 70S ribosomes 9. Bacterial chromosome 10. Plasmids |
| Differences b/w animal and plant cells | Flagella -Cell movement Cillia- short hairs moving back and forth across rhe surface of cell to move matter |
| How viruses challenge the cell theory? | 1. Viruses are acellular, they are not made up of cells 2. Although viruses contain DNA or RNA, they do not grow or reproduce on their own, maintain homeostasis nor metabolize 3. Although viruses can reproduce, they cannot grow and repeoduce on their own, and can only do so by using host's mechanisms (proteins/ATP/enzymes) |
| Living Characteristics of viruses | 1. Only reproduce/ carry out metabolic activities in the living host cell 2. contains DNA or RNA that can be passed down to progeny 3. can mutate as mutation of genetic material results in a phenotype that is best suited to adapt and survive in a particular environment(undergo natural selection) |
| Non-Living Characteristics of viruses | 1. Does not contain cytoplasm therefore cannot carry out metabolic activities (such as synthesis or organic molecules such as sugars, proteins,fats) outside the host cell 2. cannot grow and reproduce on their own therefore can only replicate inside living cells/obligate parasites 3. contains either DNA or RNA, but never both |
| Why are viruses considered obligate parasites? | 1. They lack enzymes such as DNA Polmerase and hence relies on the host cell's enzymes to replicate own viral nucleic acid 2. Unable to synthesise ATP on it own. ATP is used as a source of energy to allow metabolic acitivities to occur 3. They lack transcription amd translation machineries such as enzymes and ribosomes to translate DNA to mRNA and mRNA to polypeptides/proteins and hence relies on host cell's enzymes and ribosomes to make viral protein 4. They lack raw materials for reproduction and hence relies on the host cell's nucleotides, amino acids and ATP for the synthesis of nucleic acid and viral proteins |
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