1. CELL STRUCTURE Flashcards
Substance bacterial cell walls are made of
peptidoglycan (murein).
–> these are long molecules containg peptides and sugars
What is energy required for in a cell
- active transport
- movement
- endocytosis/exocytosis
What are cells with a high demand of energy
- liver cells
- muscle cells
What happens to metabolism when you exercise
- number of mitochondria increase
- so metabolism increases
What are the functions of mitochondria
- aerobic respiration
- synthesis of lipids
What is the process of conversion of ATP to ADP
hydrolysis
- the ADP can then be recycled back to the mitochondrion for conversion back to ATP during aerobic respiration
What is responsible for the shape of the cell
cytoskeleton made of microtubules along with actin and intermediate filaments
What are the functions of microtubules
- mechanical function of support
- part of cytoskeleton which determines cell shape
- secretory vesicles and other organelles can be transported along the outside surfaces of microtubules
- membrane-bound organelles are held in place by the cytoskeleton
- during nuclear division, the spindle used for the separation of chromatids is made of microtubules
- microtubules form part of the structure of centrioles
What is the endoplasmic reticulum
- membranes form an extended system of flattened compartments in the cell, called sacs
- process can take place inside these sacs, separated from the cytoplasm
- sacs can be interconnected to form a complete system (reticulum)
- the ER is continuous with the outer membrane of the nuclear envelope
What are ribosomes made of
RNA and protein
Function of the smooth ER
production of
- lipids
- steroids, such as cholesterol and the reproductive hormones such as oestrogen and testosterone
Where are lipids synthesised
smooth ER and mitochondria
Where are reproductive hormones made
smooth ER
What happens to proteins made in the rough ER
- proteins made in ribosomes on the rough ER enter the sacs and move through them
- the proteins are often modified in some way on their journey
- small sacs called vesicles can break off from the ER and these can join together to form the golgi body
What is the maximum resolution of a light microscope
200 nm
What ways do golgi bodies modify the molecules
- addition of sugar molecules to proteins to make glycoproteins
- removal of first amino acid, methionine, to make functioning protein
- addition of prosthetic groups such as heam to form proteins with quaternary structure
- in plants, enzymes in the golgi body convert sugars into cell wall components
- golgi vesicles are used to make lysosomes
Where are lysosomes made
golgi vesicles containing hydrolytic enzymes
What organelles have double membranes
nucleus
mitochondria
chloroplast
Functions of lysosomes
- digestion of mammary glands after lactation
- digestion of bacteria by phagocytosis forming phagolysosomes
- replacement of cartilage with bone during development by releasing enzymes outside the cell
- digestion of a path to the ovum by the acrosome
What is the acrosome
a lysosome
Properties of the ATP molecule
small, soluble
can be hydrolysed easily as it is very unstable
releases a lot of energy when hydrolysed
How is the size of ribosomes measured
- in ‘S units’
- which are a measure of how fast they sediment in a centrifuge
Evidence of endosymbiosis of mitochondria and ribosomes
- contain 70s ribosomes like those found in bacteria
- contain small, circular (loop of) DNA molecules like those found in bacteria
- replicate independently of cell division by dividing into two
Where are ribosomes found in a cell
rough endoplasmic reticulum
cytoplasm
mitochondria
chloroplasts
