biology cells topic 2 aqa

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  • Created on: 24-09-18 19:18

what is the strusture of a mitochandria

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what is the function of a mitochondria?

Mitochondria are often referred to as the powerhouse of the cell. They are small structures within a cell that are made up of two membranes and a matrix. The membrane is where the chemical reactions occur and the matrix is where the fluid is held.

The main job of mitochondria is to perform cellular respiration. This means it takes in nutrients from the cell, breaks it down, and turns it into ATP. This energy is then in turn used by the cell to carry out various functions.mitochondria is found mostly in cells that have a high level of metabolic activity and therefore require more mitochondria.

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the functions of the nucleus?

to act as the control centre of the cell through the production of mRNA and tRNA and hence protein synthesis 

retain the genetic material of the cell in the form of DNA and chromosomes

manufacture ribosomal RNA and ribosomes

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what do the nucleur pores do?

allow the passage of large molecules such as messenger RNA there are typically  3000 pores in each nucleus.

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what does the nucleoplasm do

it is the granular jelly-like material that makes up the bulk of the nucleus

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what does the cristae do?

they are extensions of the inner membrane .these provide a large surface area for the attachment of enzymes and other proteins involved in respiration

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what does the matrix do?

makes up the remainder of the mitochondrion.it contains proteins, lipids, ribosomes and DNA that allows the mitochondria to control the production of some of their own proteins. many enzymes involved in respiration are found in the matrix.

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what is the function of chloroplasts?

the granal membranes provide a large surface area for the attachment of chlorophyll, electron carriers and enzymes that carry out the first stage of photosythesis.these chemicals are attached to the membrane in a highly ordered fashion.

the fluid of the stroma possesses all the enzymes needed to make sugars in the second stage of photosynthesis

chloroplast contain both DNA and ribosomes so they can quickly and easily manufacture some of the proteins needed for photosynthesis

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endoplasmic reticulum

the ER is an elaborate three-dimensional system of sheet-like membranes, spreading through the cytoplasm of the cells.it is continuous with the outer nuclear membrane. the membranes enclose a network of tubules and flattened sacs called cisternae

RER: has ribosomes present on the outer surfaces of the membranes. its function is to provide a large surface area for the synthesis of proteins and glycoproteins and provide a pathway for the transport of materials, especially proteins, throughout the cell.

SER: lacks ribosomes on its surface and is often more tubular in appearance its function are to synthesis store and transports lipids and carbohydrates.

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golgi apparatus

the Golgi apparatus occurs in almost all eukaryotic cells and is similar to the SER in structure except that it is more compact.it consists of a stack of membranes that make up flattened sacs, or cisternae, with small rounded hollow structures called vesicles. the proteins and lipids produced by the ER are passed through the Golgi apparatus in strict sequence. the Golgi modifies these proteins often adding non-proteins compounds, such as carbs, to them.it also 'labels them, allowing them to be accurately sorted and sent to their correct destinations. once sorted, the modified proteins and lipids are transported in Golgi vesicles which are regularly pinched off from e ends of the Golgi vesicles which are regularly pinched off from the ends of the Golgi cisternae. these vesicles may move to the cell surface, where they fuse with the membrane and release their contents to the outside. 

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lysososomes

hydrolyse materials ingested by phagocytic cells, such as white blood cells and bacteria

release enzymes to the outside of the cell (exocytosis) in order to destroy material around the cell

digest worn-out organelles so that the useful chemicals they are made of can be re-used

completely break down cells after they have died

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ribosomes

80s-found in eukaryotic cells is around 25nm in diameter

70s-found in prokaryotic ells,mitochondria and chloroplasts,is slighltly smaller

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cell wall

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