Chpt 1: Cells and genomes Flashcards
what distinguishes life from other processes, such as the growth of a crystal
heredity
are most living organisms single or multi cellular
single
a living organism must consume what to exist
free energy
all cells store their hereditary information in what form
DNA molecules
what provides compelling evidence that all living things have a universal common ancestral cell
all living cells store their information in the same form or that the hereditary information carried by one type of cell should be readable by the information-handling machinery of another
describe the overall structure of DNA
- DNA is long, unbranched, paired polymer chains
- polymer chains are composed of 4 types of monomers
- monomers are chem compounds called nucelotides A,T,G,C
what is a genome
the totality of hereditary info embodied in the linear sequence of nucleotides in somethings DNA
all cells replicate their hereditary info how
by templated polymerization
describe the structure of a nucleotide
- deoxyribose sugar
- phosphate group
- base (ATGC)
how many bonds between G C
3
how many bonds between A T
2
what kind of bonds are between 2 nucleotides (forming the chain)
sugar-phosphate linkages
what gives a DNA molecule directionality/ polarity
cause the sugar-phosphate is asymmetric
what differs in regards to DNA replication in diff cells
- diff rates of DNA replication
- diff controls to start/ stop it
- diff auxiliary molecules to help the process along
what sugar is in RNA
ribose
how many AA are there
20
what makes up proteins
AA
do all cells do translation the same way
yeah
a codon codes for what
a single AA
the genetic code is read out by what
tRNA
what is a gene
the segment of DNA sequence corresponding either to a single protein or to a single RNA molecule
what are the three major domains of life
- eukaryotes
- bacteria
- archaea
what helps us to determine the evolutionary distance between 2 organisms
- the number of differences between their DNA sequences
- we look at their rRNA sequences
bacteria and archaea are both what kind of living organism
prokaryotes
what are the most diverse group of organism on the planet
bacteria
describe the structure of bacteria
- spherical or rod-shaped
- only a few micrometers
- have a cell wall and cytoplasm with all the proteins they need
which is the most poorly understood domain of life
archaea
what are phototrophic organisms
feeding on sunlight
what are lithotrophic organisms
feeding on rock
what are organotrophic organisms
feeding on other living things ot the organic chemicals they produce
DNA, RNA and protein are composed of which elements
- hydrogen
- nitrogen
- carbon
- oxygen
- sulfur
- phosphorus
how do organisms evolve
through a process of mutation and natural selection
essential genes (needed for survival) are ________-
highly conserved
what is an intragenic mutation
an existing gene can be randomly modified by changes in its DNA sequence, through various types of errors that occur in the process of DNA replication and DNA repair
what is gene duplication
an existing gene can be accidentally duplicated, creating a pair of initially identical genes within a single cell; these two genes may then diverge in the course of evolution
what is DNA segment shuffling
two or more existing genes can break and rejoin to make a hybrid gene consisting of DNA segments that originally belonged to separate genes.
what is horizontal/ intercellular DNA transfer
a piece of DNA can be transferred from the genome of one cell to that of another—including between species. This process contrasts with the usual vertical transfer of genetic information from parent to progeny
what are gene families
a set of several similar genes, formed by duplication of a single original gene, and generally with similar biochemical functions
what are orthologs
genes in two separate species that derive from the same ancestral gene in the last common ancestor of those two species
what are paralogs
Related genes that have resulted from a gene duplication event within a single genome—and are likely to have diverged in their function
what are homologs
Genes that are related by descent as either orthologs or paralogs
why are family relationships among genes important
- evolutionary interest
- they simplify the task of deciphering gene functions
what is this
paralog
what is this
orthologs
what information processing and metabolism. aspects are common to all 3 domains of the living world (think of the green chart)
- translation
- AA transport and metabolism
compare prokaryotes and eukaryotes: nucleus
- prokaryotes no *does have nucleoid region)
- eukaryotes yes
compare prokaryotes and eukaryotes: transcription location
- prokaryotes cytoplasm
- eukaryotes nucleus
compare prokaryotes and eukaryotes: translation location
- prokaryotes cytoplasm
- eukaryotes cytoplasm
compare prokaryotes and eukaryotes: cell membrane additions
- prokaryotes hopanoids
- eukaryotes sterols (cholersterol)
compare prokaryotes and eukaryotes: size
- prokaryotes smaller
- eukaryotes larger
compare prokaryotes and eukaryotes: ratio of surface area to volume
- prokaryotes higher
- eukaryotes lower
compare prokaryotes and eukaryotes: internal organization
- prokaryotes none
- eukaryotes has them
where do eukaryotes store their DNA
- in the nucelus
- small amounts inside the organelles that evolved from captured bacteria
do mitochondria have small or large genomes
small
which domains of life have the largest genomes
eukaryotes
why can we use model orgaisms
because all cells appear to have descended from a common ancestor, whose fundamental properties have been conserved throughout evolution
the analysis of gene functions depends on which approaches
- biochemistry (directly examines the functions of purified molecules)
- genetics (focuses on mutants)
why is ecoli used as a model organism
- can be grown in a culture bottle or dish
- can reproduce every 20 mins ish
- evolves at a remarkable speed
why is yeast used as a model organism
- small genome size (easier to look at )
- single cellular
- easy to work with (replicates easy and can be stored in a freezer to be used later)
- easily cultured
- used to study eukaryotic processes like cell division
why is arabidopsis used as a model organism
- Small weed that can be grown indoors in large numbers
- Produces 1000s of offspring per plant after 8-10 weeks
- Close evolutionary relationship between flowering plants
- very huge genome
why is c. elegans used as a model organism
- 1st multicellular organism to have entire genome sequence determined
- very small
- can be frozen indefinitely
- develops with clockwork precision (exactly 959 body cells)
why are drosophila used as a model organism
- Very similar to other vertebrates
- Short breeding time, and cheap and easy
- Typically feel ethical
what is the predominant mammalian model organism
mouse
why are frogs used as a model organism
eggs are big, easy to manipulate, and fertilized outside the animal
why are zebrafish (d. rerio) used as a model organism
- genome is compact
- generation time of only about 3 months
- many mutants are available
- genetic manipulation is simple
- Transparent embryos that develop outside the mother
- Can observe cells moving and changing throughout development
briefly describe hox genes and drosophila
the antp gene grows legs where the antennas should be
