Cell Bio PCB 3023 - Exam 1
Heterochromatin - Regions in chromosome where fibers are highly condensed
Few genes - resistant to transcription by not completely exempt
Concentrated in centromeres and telomeres
What is a simple genome and which type of cell has one? - Codes for fewer proteins then a
complex genome, prokaryotes
Plant cell walls were.... - Reacquired after eukaryotes lost cell walls when they diverged from
prokaryotes
Genes - Regions of DNA transcribed into any type of RNA
What are RNPs? Examples - Ribonucleoproteins, ribosomes in all cells and telomerase +
spliceosome in eukaryotes
Regulation of gene expression in prokaryotes vs eukaryotes - More control in eukaryotes allows
for cells to differentiate by expressing different regions of the DNA in different cells
Homeostatic disequilibrium - Constant state of cell that requires a lot of energy to maintain
How to organisms get carbon and nitrogen? - CO2 fixed by phototrophs using sunlight and stored
in carbohydrate molecule, N2 converted to ammonia by bacteria
Why are carbohydrates important? - Energy from sunlight used to break CO2 ends up in covalent
bond of carbohydrate. The molecule serves as a high energy source of carbon that releases energy when
carbon is removed
, Why are organisms so complex now? - evolution stumbled upon things that made doing basic
things easier - extra proteins etc
Mycoplasma genitalium - 477 proteins needed for life
Homologs - two or more genes descended from the same common ancestral gene, gene families,
can describe genes or proteins
Orthologs - Genes in two separate species that derive from the same ancestral gene in the last
common ancestor of those two species
Paralogs - Related genes that have resulted from a gene duplication event within a single genome
Gene Family creation - Duplication, intragenic mutation, segment shuffling, horizontal transfer
Intragenic Mutation - errors during replication may result in slightly new sequences
Segment shuffling - accidental breaks in two or more gene regions are mis-repaired such that a
new, hybrid gene sequence results
Horizontal transfer examples - Viruses, acquisition of environmental DNA, sexual reproduction,
vertical transfers
How did accidental acquisition of nuclear envelope cause the rest of the characteristics of a eukaryotic
cell? - In prokaryotes a larger genome would interfere with cell processes. the nucleus allowed
DNA to increase in size - made more proteins - cell got bigger - genome could get even bigger. Packaging
methods were needed bc of large genome - chromosome structure
Why did cytoskeleton develop? - Large cell needed support (internal membranes defining
organelles). Without cell wall could engage in phagocytosis. Plants reaquired cell wall as they
transitioned to land growth
Heterochromatin - Regions in chromosome where fibers are highly condensed
Few genes - resistant to transcription by not completely exempt
Concentrated in centromeres and telomeres
What is a simple genome and which type of cell has one? - Codes for fewer proteins then a
complex genome, prokaryotes
Plant cell walls were.... - Reacquired after eukaryotes lost cell walls when they diverged from
prokaryotes
Genes - Regions of DNA transcribed into any type of RNA
What are RNPs? Examples - Ribonucleoproteins, ribosomes in all cells and telomerase +
spliceosome in eukaryotes
Regulation of gene expression in prokaryotes vs eukaryotes - More control in eukaryotes allows
for cells to differentiate by expressing different regions of the DNA in different cells
Homeostatic disequilibrium - Constant state of cell that requires a lot of energy to maintain
How to organisms get carbon and nitrogen? - CO2 fixed by phototrophs using sunlight and stored
in carbohydrate molecule, N2 converted to ammonia by bacteria
Why are carbohydrates important? - Energy from sunlight used to break CO2 ends up in covalent
bond of carbohydrate. The molecule serves as a high energy source of carbon that releases energy when
carbon is removed
, Why are organisms so complex now? - evolution stumbled upon things that made doing basic
things easier - extra proteins etc
Mycoplasma genitalium - 477 proteins needed for life
Homologs - two or more genes descended from the same common ancestral gene, gene families,
can describe genes or proteins
Orthologs - Genes in two separate species that derive from the same ancestral gene in the last
common ancestor of those two species
Paralogs - Related genes that have resulted from a gene duplication event within a single genome
Gene Family creation - Duplication, intragenic mutation, segment shuffling, horizontal transfer
Intragenic Mutation - errors during replication may result in slightly new sequences
Segment shuffling - accidental breaks in two or more gene regions are mis-repaired such that a
new, hybrid gene sequence results
Horizontal transfer examples - Viruses, acquisition of environmental DNA, sexual reproduction,
vertical transfers
How did accidental acquisition of nuclear envelope cause the rest of the characteristics of a eukaryotic
cell? - In prokaryotes a larger genome would interfere with cell processes. the nucleus allowed
DNA to increase in size - made more proteins - cell got bigger - genome could get even bigger. Packaging
methods were needed bc of large genome - chromosome structure
Why did cytoskeleton develop? - Large cell needed support (internal membranes defining
organelles). Without cell wall could engage in phagocytosis. Plants reaquired cell wall as they
transitioned to land growth
