1. Cells and Genomes Flashcards
the study of the structure, function, and
behavior of cells
cell biology
distinguishes life from other processes,
in which orderly structures are generated
but without the same type of link between the peculiarities of parents and the peculiarities of offspring
heredity
“the key to every biological problem must finally be sought in the cell; for every living organism is, or at some time has been a cell”
E.B. Wilson
ribose, uracil (U) in place of thymine (T)
RNA
what is the base
phosphate group
long, unbranched, paired polymer chains,
formed always of the
same four types of
monomers.
DNA
All living cells on Earth store their hereditary information in the form of _ _ _ _ _ _
double-stranded
molecules of DNA
The shape of the RNA molecules may enable it to
recognize other molecules by binding to them selectively
Production of two other key
classes of polymers
RNA and proteins
nucleotide, consists of two parts: sugar and phosphate group
monomer
4 bases
Adenine, guanine, cytosine, thymine
DNA to RNA
transcription
RNA to proteins
translation
RNA transcripts are
mass-produced and disposable
molecules that guide the synthesis of proteins according to the genetic instructions stored in the DNA
messenger RNA
Function of RNA, it intermediates … ?
intermediates in the transfer of genetic information
RNA molecules have distinctive structures that can also …?
give them specialized chemical capabilities
interspersed among the segments
that code for protein; expression of individual genes
regulatory DNA
Protein carries information in the form of a
the linear sequence of symbols
monomer of proteins; 20 type
amino acids
a segment of DNA sequence
corresponding to a single protein or
set of alternative protein variants or
to a single catalytic regulatory, or
structural RNA molecule
gene
each cell is enclosed by a
plasma membrane
consisting of a hydrophobic (water-insoluble) and a hydrophilic (water-soluble) parts, creating a bilayer
amphiphilic
largely determine which molecules enter the cell
membrane transport proteins
the minimum number of
genes far a viable cell
not less than 300
a living cell with 530
genes, about 400 of which
are essential
mycoplasma genitalium
DNA sequence of any given
organism can be readily
obtained by _ _ _
standard biochemical techniques
feeding on other living things or
the organic chemicals they produce
organotrophic
prokaryotes live mostly as __ __or in loosely organized communities
independent individuals
feeding on rock
lithotrophic
feeding on sunlight
phototrophic
DNA, RNA, and protein are composed of just six elements
H, C, N, O, S, P
3 primary branches
archaea, bacteria, eukaryotes
genes that are related by descent
orthologs
may represent a change for the
better or cause serious damage
alterations of nucleotide sequence
mutations and natural selection –
evolution of organisms
Prokaryotic cells live in an enormous variety of
ecological niches
their genomes are small, with
genes packed closely together and minimal quantities of regulatory DNA between them
prokaryotic cell
detailed genome analyses have
recently revealed that the first
eukaryotic cell formed after a
a particular type of
ancient archaeal cell engulfed an ancient bacterium
readily interpret such close family
resemblances in terms of evolution from
common ancestor
function of molecules
biochemistry
4 modes of genetic innovation
- Intragenic mutation
- Gene duplication
- DNA segment shuffling
- Horizontal transfer
related genes that resulted from a gene duplication event
paralogs
The analysis of gene functions
depends on two complementary
approaches
genetics and biochemistry
small, rod-shaped bacteria. they are grown easily on simple
nutrient broth
Escherichia coli
transfers occur much more frequently between different species of prokaryotes
horizontal gene
study of mutant
genetics
keeps the structure of the cell
cytoskeleton
from parent to offspring,
sexual reproduction causes a
large-scale horizontal transfer of
genetic information between two
initially separate cell lineages—
those of the father and the
mother
vertical transfer
have a remarkable capacity to
take up even nonviral DNA
molecules from surroundings,
and thereby capture the
genetic information
horizontal gene transfer
modern eukaryotic cells envolved from a symbiosis
mitochondria originated from free-living oxygen-metabolizing
(aerobic) bacteria that were engulfed by an ancestral cell that could otherwise make no such use of oxygen (that is, was anaerobic).
bigger and more elaborate than
prokaryotic cells, and their genomes are bigger
eukaryotic cells
possesses mitochondria
and have a tough outer wall
fungi
adapts to variable chemical
conditions and reproduces
rapidly, evolve by mutation and
selection at a remarkable
speed
E. coli
plant cells lost the ability to do
phagocytosis having a
tough, protective cell wall
first eukaryotic cells formed
after an
archaeal cell engulfed an aerobic
bacterium
they have their own
genome; originated as
symbiotic photosynthetic
bacteria
mitochondria and
chloroplasts
Has Been Chosen Out of
300,000 Species As a Model Plant
Arabidopsis
they act by binding, directly or
indirectly, to the regulatory
DNA adjacent to the genes
that are to be controlled, or
by interfering with the
abilities of other proteins to
do so
transcription regulators
regulate the expression of adjacent genes
regulatory DNA
_____ has ___ DNA that does not code for protein
compare to ________
eukaryotes, more, prokaryotes
how many of human genome do not code for proteins?
98.5%
model organisms for molecular
genetic studies (5)
- nematode worm Caenorhabditis
elegans - the fly Drosophila melanogaster
- the zebrafish Danio rerio
- the mouse Mus musculus
- the human, Homo sapiens
small, single-celled; closely
related to animals as it is to
plants
Saccharomyces cerevisiae
vertebrate genome: whole-genome duplications do occur
from time to time in evolution
frog genus Xenopus
how to trace the chain of
cause and effect from the
genetic instructions encoded
in the chromosomal DNA to
the structure of the adult
multicellular body
Drosophila melanogaster
why arabidopsis?
produces thousands of
offspring per plant after
8-10weeks
compact genome, generation time of 3 months, many mutants are known, and genetic engineering is relatively easy
zebrafish
embryonic development: eggs are big, easy to manipulate, fertilized outside the animal
frogs
predominant Mammalian
Model Organism
mouse
Why mouse is considered for mammalian model organism?
many naturally occurring mutations are known, often
mimicking the effects of corresponding mutations in
humans
catalog our own
genetic disorders
humans
