B2.2 Organelles and Compartmentalisation Flashcards

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1
Q

Compartmentalisation

A

One of the carbon compound thought to have been present on early Earth was fatty acids.

When place in water they form vesicles, and the boundary is used in compartmentalisation in the first cell.

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2
Q

RNA as the First Genetic Material

A

Hypothesis: Ribonucleic acid (RNA) acted initially as both the genetic material and the enzymes of the earliest cells

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3
Q

Evidence of RNA as the first genetic material

A

RNA can assemble spontaneously from simpler organic molecules (nucleotides)

RNA can form copies of itself (self-replicate)

RNA can control chemical reactions (catalytic role), e.g. ribozymes are still used in modern cells to remove introns and allow faster development of peptide bond

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4
Q

LUCA

A

Last universal common ancestor

The genetic code is universal, and all life shares a common mechanism of transcription and translation

Certain genes are broadly distributed across all cellular organisms

Similar transport mechanisms for cellular materials in and out of cells, as well as within cells

LUCA does not represent the first cellular organism and it is probable that the other lifeforms coexisted at the time of the LUCA.

It is hypothesized that the other forms of life would demonstrate distinctive characteristics other than what the LUCA had.

The other life forms are not present today might be the result of unsuccessful competition with the LUCA and its descendants.

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5
Q

Estimating the Dates of the First Living Cells and LUCA

A

Estimating dates using microbes in fossils
Biochemical evidence in sediment (Biosignatures)
Phylogenetic comparisons
Molecular clock

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6
Q

The Location of the Origin of Life

A

LUCA is hypothesized to exist in the vicinity of hydrothermal vents.

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7
Q

hydrothermal vents

A

a heat source some into close contact with fluid system within the Earth’s crust, resulting in the convective flow of fluid to the seafloor

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8
Q

evidence of LUCA

A

Some of the oldest fossilised traces or precipitates have originated at these vents

LUCA is also thought to have possessed a gene that is currently found in extremophiles living near the vents

Presence of mineral-rich environment with both acidic and basic fluids that are necessary for chemical reactions

Presence of both hydrogen and carbon dioxide at these locations, resulting in the reducing environment for carbon compound formation

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9
Q

cell compartmentalisation

A

Organelles are discrete subunits of cells that are adapted to perform specific functions

Cell wall, cytoskeleton and cytoplasm are not considered as organelles.

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10
Q

All eukaryotic cells possess compartments that are involved with:

A

Energy production
Metabolism
Biosynthesis
Degradation

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11
Q

structures of mitochondrion

A

outer mitochondrial membrane
matrix
cristae
inner mitochondrial membrane
space between inner and outer membrane

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12
Q

outer mitochondrial membrane

A

a membrane that separates the contents of the mitochondrion from the rest of the cell

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13
Q

matrix

A

an internal cytoplasm-like substance that contains the enzymes for the first stages of respiration that take place in the mitochondria (the link reaction and the Kreb cycle)

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14
Q

Cristae

A

Tubular regions surrounded by membranes that increase the surface area for reactions that take place towards the end of respiration (oxidative phosphorylation)

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15
Q

inner mitochondrial membrane

A

a membrane that contains the carriers and enzymes for the final stages of respiration (electron transport chain and chemiosmosis )

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16
Q

space between inner and outer membranes

A

a reservoir for hydrogen ions (protons, allowing a high concentration of protons

17
Q

structures of chloroplasts

A

extensive membrane surface area of the thylakoids

small space (lumen) and low volumes of fluid within the thylakoids

stroma region similar to the cytoplasm of the cell and the matrix of the mitochondrion

double membrane on the outside

18
Q

extensive membrane surface area of the thylakoids

A

Greater absorption of light by photosynthesis

19
Q

small space (lumen) and low volumes of fluid within the thylakoids

A

faster accumulation of protons to create a concentration gradient

20
Q

stroma region similar to the cytoplasm of the cell and the matrix of the mitochondrion

A

provides a region where the enzymes necessary for the Calvin cycle can work

21
Q

double membrane on the outside

A

isolates the working parts and enzymes of the chloroplast from the surrounding cytoplasm

22
Q

nucleus structure

A

nuclear envelope
nuclear pore
nucleolus
chromatin

23
Q

nuclear envelope

A

Provides an area where DNA can carry out its functions without being affected by the processes in other parts of the cell.

24
Q

nuclear pore

A

Allow ions and small molecules to diffuse through and control the passage of mRNA

25
Q

nucleolus

A

Contains RNA-Protein complex, where ribosomes are made

26
Q

chromatin

A

Contains inactive DNA

27
Q

ribosome

A

Site for protein synthesis (translation)
Ribosomes are made of proteins and ribosomal RNA (rRNA)

The small subunit
- mRNA binding site
The large subunit
- Three tRNA binding sites
(aminoacyl (A) site, peptidyl (P) site, exit (E) site)

Ribosomes can be found either freely floating in the cytoplasm or bound to the rough ER (in eukaryotes)

Ribosomes differ in sizes in prokaryotes and eukaryotes (70S for prokaryotes, 80S for eukaryotes)

28
Q

4 types of vesicles

A

Peroxisome
Lysosome
Transport vesicle
Secretory vesicle

29
Q

transport vesicle

A

moves molecules within the cell

30
Q

secretory vesicle

A

contains materials that are to be excreted from the cell, such as neurotransmitters (involved with the nerve and muscle action) and hormones (control many general functions in plants and animals)

31
Q

what are clathrins

A

Clathrins are proteins in the cell membrane that anchor certain proteins to specific sites.
Lined up at coated pits and allow the molecules to bind to specific receptors.
Pit then deepens and seals off