mitochondria, lysosomes and peroxisomes Flashcards
what is a mitochondrion
a membrane enclosed organelle that is around 1-10um in size, and is responsible for producing ATP
what are mitochondria involved in
cell signalling, cell differentiation, cell death and control of the cell cycle/ growth
what does ATP require to work and why?
2 molecules of magnesium to cancel the -4 charge ATP carries
where are the majority of mitochondria found
in all aerobic eukaryotic cells, but mainly in regions of greatest metabolic activity e.g. muscles
how did mitochondria arise and how do we know this
endosymbiotic theory - mitochondria are descended from ancient bacteria, which ere engulfed by the ancestors of eukaryotic cells more than billions of years ago.
mitochondria contain organelles themselves
what do mitochondrial proteins vary upon
the tissues they are found in and what species they are in
how many distinct types of mitochondrial proteins do humans have in cardiac mitochondria
615
what does the mitochondrial outer membrane contain
large numbers of integral proteins called porins (basically tubes/channels)
how do larger proteins get across the mitochondrial outer membrane
they have a signalling sequence to utilise an active transport protein called translocase
what can disruption of the outer membrane of a mitochondrion cause?
cell death as it allows proteins in the intermembrane space to leak into the cytosol
what is the intermembrane space in a mitochondrion
the space between the inner and outer membrane
name the protein localised to the intermembrane space and what it’s used in
cytochrome c - part of the electron transfer train
name the 4 functions of the proteins in the inner membrane
- perform redox reactions of oxidative phosphorylation
- generate ATP in the matrix - ATP synthase
- specific transport proteins that regulate metabolite passage into and out of the matrix
- protein import machinery
why do we need to control what goes into and out of the inner membrane in mitochondria
water is able to hydrolyse ATP
what do cristae do
expand the cell surface of the inner mitochondrial membrane and enhance its ability to produce ATP
what does the mitochondrial matrix contain
proteins, enzymes, special ribosomes, tRNA, and several copies of the mitochondrial DNA genome
how many base pairs dose mitochondrial DNA have and how many genes - what are they split into
16568 base pairs
37 genes
- 13 protein encoding regions for respiratory complexes
- 2 for rRNAs
- 22 tRNAs
what do mitochondrial diseases cause and what can they lead to
genetic defects of muscle or nerve tissue
severe - infant death, blindness, deafness, seizures
milder - muscle weakness, intolerance of exercise
what are lysosomes
membrane-bound sacs containing a range of hydrolytic enzymes (acid hydrolases) for intracellular digestion
what are the two functions of lysosomes
- digest; excess or worn-out organelles , food particles, engulfed viruses or bacteria
- fuse with and dispense enzymes into vacuoles to digest their contents
what does the lining of a lysosome allow
the digestive enzymes inside the lysosome to work at acidic pH
name a few of the enzymes found in lysosomes
- Acid hydrolases
- Nucleases
- Proteases
- Glycosidases
- Lipases
- Phosphatases
- Sulphatises
- Phospholipases
what is a peroxisome
ubiquitous membrane-bound organelles in eukaryotic cells that contain a crystal or urate oxidase - main function is to detoxify cells
what are the functions of peroxisomes
- Participate in the metabolism of fatty acids and other metabolites
○ Beta-oxidation
○ Fatty acids are broken down 2 carbons at a time, converted to acetyl-CoA, which is then transported back to cytosol- Contain enzymes that rid cells of toxic peroxides
- Part of secretory pathway
