Year 9 Cell structure - PowerPoint Presentation

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Year 9 Cell structure

Functions of organelles

OrganelleFunctionPlant or animalNucleusContains genetic material, which provides the instructions to control the activities of the cell.BothCytoplasmMost chemical processes take place here, controlled by enzymesBothCell membraneControls the movement of substances into and out of the cellBothMitochondriaMost energy is released by respiration hereBothRibosomesSite of protein synthesisBothCell wallStrengthens the cell to reduce risk of shrinking and bursting.Plant ONLYChloroplastsContain chlorophyll, absorbs light energy for photosynthesisPlant ONLYPermanent vacuoleFilled with cell sap to help keep the cell turgidPlant ONLY

All living things are made up of cells. The structures of different types of cells are related to their functions.

Prokaryotic cellsBacteria

Comparing Prokaryotic and Eukaryotic

ProkaryoticEukaryoticNo membrane bound nucleusMembrane bound nucleusDNA is single strandedDNA is double strandedMay contain plasmidsDo not contain plasmidsSmallerLarger

Eukaryotic cells

Standard form

Keywords

Keyword

DefinitionUnicellularSingle celled organismsMulticellularOrganisms that consist of more than one cellProkaryoteA unicellular organism that has no membrane bound organelles. Genetic material is not membrane boundEukaryoteA cell from any organism that contains membrane bound organelles, can be multicellular or unicellular. Genetic information is stored within a nucleus. OrganelleStructures found within cells that have specialised functionsMembrane bound organelleOrganelles found within cells with specialised functions and are surrounded by a plasma membrane e.g chloroplast, mitochondria

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Year 9 Cell structure

Cells are specialised for a particular function. Structure helps them to carry this function out.

Specialised CellsCellDiagramFunctionAdaptationsSperm cellTransport the male DNA to the female DNA.Long tail – to swim.Lots of mitochondria – for energy.Enzymes in head – to digest egg cell membrane. Haploid. Nerve cellTo carry electrical signals from one part of the body to another.Long – to cover distance.Branched connections – to connect to other nerve cells. Insulated with Myelin.Muscle cellTo contract quickly.Long – so that they have space to contract. Work collectively.Lots of mitochondria – to generate energy for the contraction.Root hair cellsTo absorb mineral ions and water from the soil.Long hairs – to stick into soil.Big surface area – to absorb more water and mineral ions. Many mitochondria.Xylem cellsTo transport water in plants.Hollow in the centre – to allow water to flow through. Phloem cellsTo transport food in plants.Very few subcellular structures – to allow food to pass through.Cell body outside of phloem. Cell differentiationDifferentiation is the process by which a cell changes to become specialised for its job.As cells change, they develop different subcellular structures and turn into different types of cells.In most animal cells, cell differentiation mostly occurs when the baby develops in the wombPlant cell contain meristem tissue at the roots, buds, shoots and tips and these retain the ability to differentiate throughout the life of the organismThe cells that differentiate in mature animals are mainly used for repair and replacing cells (e.g. skin or blood cells). Differentiation is caused by genes being switched on and off.

Undifferentiated cells are called STEM CELLS, and can give rise many more cells of different types from which certain other cells can arise from differentiation.In some countries stem cell research is banned. In the UK it is allowed as long as it follows strict guidelines

Arguments for and against the use of STEM cells

For

AgainstAdult Stem cells come from bone marrow and can replace faulty blood cells. Less chance of rejection. Adult stem cells can only differentiate into a small number of different cells so cannot treat all illnessesEmbryonic stem cells could replace faulty cells in sick people and help cure disease.

E.g diabetesEmbryonic stem cells shouldn’t be used as each embryo is a potential human life which has to be destroyed.Embryos are usually from fertility clinics, they are embryos not used in IVFAdult stem cells have to be removed during an operation which is painfulTherapeutic cloning – embryo could be made to have the same genetic information as the patient so they wouldn’t be rejected by the bodyThe use of stem cells has potential risks such as transfer of viral Infection.

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