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Cells
Cells as the basis of life definitions 2021 revision
| Term | Definition |
|---|---|
| List some of the cell theory | All living organisms are made of cells, cells can only arise from pre existing cells, cells contain hereditary material |
| What are the major two cell types | Prokaryotic and Eukaryotic |
| The cell membrane is made up of a... | Phospholipid bilayer |
| What is the role of a phospholipid bilayer | It separates the cell from its surroundings and controls the exchange of materials such as nutrients and wastes between the cell and its environment |
| What is the hydrophobic component of the cell membrane | The lipid tails |
| What is the hydrophilic component of the cell membrane | The phosphate heads |
| In the fluid mosaic model fluid refers to | The phospholipid bilayer is viscous and individual proteins and phospholipids can move positions |
| In the fluid mosaic model mosaic refers to | The phospholipid bilayer is embedded with proteins in a mosaic of components |
| The cell membrane's semi permeable feature only | permits the transport of certain substances across the membrane in order to differentiate the internal and external environment. |
| The proteins in a cell membrane are split into | Integral and peripheral proteins |
| Why do prokaryotic and eukaryotic cells have many features in common? | It is a reflection of their common evolutionary past |
| Which type of cell only exists as a single cell | Prokaryotes |
| Which type of cell has specialized organelles that facilitate biochemical reactions | Eukaryotes |
| What is the shape of DNA in prokaryotes | Circular |
| What is the shape of DNA in eukaryotes | Linear |
| How many chromosomes in a eukaryotic cell | Two or more |
| How many chromosomes in a prokaryotic cell | One chromosome |
| Does a eukaryotic cell have a cell wall | Plant cells - made of cellulose |
| Nucleus | Contains DNA. Controls all cell activity, directly involved in protein synthesis and regulates transcription |
| Nucleolus | Composed of DNA, RNA and proteins. Formation of ribosomes. Site of rRNA synthesis |
| Mitochondria. | Outer and inner membrane (cristae and matrix). Site of aerobic respiration. Creates ATP that provides cell with energy |
| Smooth Endoplasmic Reticulum | No ribosomes. Lipid synthesis |
| Rough Endoplasmic Reticulum | Ribosomes. Intracellular transportation of vesicles and site of protein synthesis on the ribosomes |
| Golgi Body | Process and package vesicles for movement out of the cell by exocytosis. Secretion of substances (proteins) |
| Vacuoles | Storage of food, nutrients, wastes and transport and export of substances in and out of the cell |
| Lysosomes | Contains enzyme. Breaks down non-functional organelles, debris, materials brought into the cell by endocytosis. Has the ability to digest substances. |
| Ribosomes | Made of rRNA and proteins. Site of protein synthesis |
| Chloroplast | Outer and Inner membranes (thylakoids, grana). Site of photosynthesis |
| Centriole | Consists of microtubules. Involved in cell division and formation of cilia and flagella. |
| Cytoskeleton. | Supports and enables for movement of organelles inside cell. Assembly of spindle. Maintenance of shape of the cell |
| Which type of cell doesnt have a cell wall | Animal cell |
| What type of cell doesnt contain chloroplasts | Animal cell |
| What are the differences in vacuoles in plants and animal cells | Animal - smaller, numerous, temporary. Plant - larger, fewer, permanent |
| Which cell doesn't contain lysosomes | Plant cells |
| What are the different forms of energy | Chemical, Light, Heat (thermal), Kinetic |
| Autotrophs | have the ability to make all energy rich compounds they need from simple inorganic substances with energy. |
| Heterotrophs | cannot create complex organic substances from simple inorganic substances and rely on autotrophs. |
| What is the main source of energy for life | The sun |
| Photosynthesis | process in which light energy is used to synthesis simple inorganic substances from complex inorganic substances. |
| If the total energy released when new bonds are made is greater than the energy required to break the original bonds | there will be a net output of energy. |
| Energy is required to break chemical bonds and... | energy is released when new bonds are formed |
| Factors affecting photosynthesis | Light, Carbon dioxide concentration, temperature |
| ATP | cells immediate source of energy |
| How is cellular energy (ATP) obtained from chemical energy? | Respiration |
| How many pyruvic acid molecules are produced from 1 glucose molecule | 2 |
| Aerobic respiration | With oxygen |
| Anaerobic respiration | Oxygen not available - less energy released, process called fermentation |
| Importance of fermentation | Commercial importance, winemaking, brewing, yeast in baking industry |
| ow many ATP do aerobic and anaerobic respiration yield | Anaerobic - 2. Aerobic - 36 |
| What cell does fermentation occur in | Eukaryotes and bacteria (e.g. sour foods) |
| Some bacteria can further break down lactic acid into | ethanol and carbon dioxide |
| Diffusion | overall movement of a substance in a fluid from a region of higher concentration of the substance towards regions of lower concentration of the substance. |
| Why is diffusion a passive process | it does not require any expenditure of energy by the cell. |
| Facilitated diffusion | channel proteins or transport proteins assist the movement of substances such as glucose, amino acids and ions across the concentration gradient from a region of higher concentration to lower concentration, the process is known as facilitated diffusion. |
| Osmosis | Refers to the net movement of solvent across a semi-permeable membrane towards a region of higher solute concentration. |
| Active transport | Opposite to diffusion, since substances are moved across the membrane against the concentration gradient. |
| Role of transport proteins | speed up the movement of a substance across the membrane. |
| Endocytosis | Some cells are able to take in particles or large molecules by enclosing them in a membranous vacuole. |
| Phagocytosis | Involves the intake of particles and is sometimes referred to as ‘cell-eating’. |
| Pinocytosis | involves the intake of liquids and large molecules into tiny vesicles that form at the surface of the cell. |
| Exocytosis | Secretion of materials produced by the cell usually involves packaging the material into a vesicles which migrates to the plasma membrane with which it fuses and then releases its contents to the outside (golgi/endo reticulum) |
| Factors affecting transport of materials | Surface area to volume ratio, size and charge, concentration gradient |
| Explain surface area to volume ratio | As cell size increases, their surface area to volume ration decreases. |
| Cell metabolism | The biochemical process that takes place in the cell is known as cell metabolism. |
| Biochemical processes are influenced by | The nature and arrangement of membranes and presence of specific enzymes |
| Explain why energy pathways involve many small, regulated steps | Small steps produce small quantities of energy that and be trapped by energy containing molecules such as ATP which can be used later. |
| Explain why the amount of DNA in a cell doubles before division | ensures each new cell has the same amount of DNA. |
| Diploid number | Two copies of each chromosome |
| Haploid number | One copy of each chromosome |
| What is asexual reproduction | Binary fission |
| Mitosis | DNA from the original cell is equally divided between the two daughter cells |
| Interphase | DNA is replicated. To separate chromatin strands into 2 identical sets, the chromatin condenses. |
| Prophase | Nuclear envelope disintegrates. Spindle begins to form.In animal cells, centrioles divide and migrate to pols of the spindle |
| Metaphase | The chromosomes line up at the equator also known as the metaphase plates and attached to the spindle by their centrioles. |
| Anaphase | The stage where the sister chromatids separate by moving to opposite poles. |
| Telophase | Two nuclear envelopes form around the two sets of chromosomes. The nucleoli reappears and the short, thickened chromosomes lose their distinctive appearance and revert to long thin strands that are only visible under the electron microscope. |
| Cytokinesis | Ensures that the cytoplasmic contents are divided between the two cells. |
| Meiosis | Produces gametes or sex cells |
| Prophase 1 | Chromatin condenses and chromosomes become visible, each consisting of identical sister chromatids. Homologous chromosomes pair up forming a bivalent and a process called crossing over occurs. |
| Crossing over | The homologous chromosomes each consisting of two identical sister chromatids lie next to each other. Enzymes cut out identical sites on non-sister chromatids and sections of DNA swap between them. |
| Metaphase 1 | The pairs of homologous chromosomes (bivalents) are moved to the equator of the cell. |
| Anaphase 1 | The homologous pairs have been randomly arranged at the equator and now separate or assort independently – one chromosomes of each pair goes to each pole of the cell. |
| Telophase 1 | Chromosomes arrive at the poles of the cell and the spindle breaks down and disappears. Two haploid cells are formed. |
| Prophase 2 | Chromosomes condense and the nuclear envelope breaks down, if needed. The centrosomes move apart, the spindle forms between them, and the spindle microtubules begin to capture chromosomes. |
| Metaphase 2 | The chromosomes each consisting of 2 identical sister chromatids are attached to the spindle fibres and moved to the equator. |
| Anaphase 2 | The sister chromatids of each chromosomes are separated and move to the opposite poles. |
| Telophase 2 | Spindle fibres disappear and the nuclear membrane reforms. Nucleolus becomes visible and the chromosomes decondense to elongate and form chromatin and are no longer visible as separate structures. |
| Overall result of meiosis | One diploid gamete cell produces 4 haploid cells either male or female. |
| Sources of variation in sexual reproduction | Crossing over, independent assortment, fertilisation, mutation |
| Cancer | uncontrolled cell division - arise from mutations |
| Three main causes of mutagens | Chemical carcinogens, radiation, viruses |
| Examples of cell culture | Genetics, cosmetics, medicine, stem cell research |
Created by:
biology2021
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