Module 1A- Cell and Genomes Flashcards
The study of the structure, function, and behavior of cells
Cell biolgy
What do the cell biology study?
Structure, function, and behavior of cells
āthe key to every biological problem must finally be
sought in the cell; for every living organism is, or at some
time has been, a cellā
E.B. Wilson
Despite their apparent diversity, living things are fundamentally ___inside
similar
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
All Cells Store Their Hereditary Information in the Same Linear Chemical Code: ____
DNA
where do all living cells on Earth store their hereditary information
in the form
of double-stranded
molecules of DNA
- long, unbranched, paired polymer chains
- formed always of the same 4 types of monomers
DNA
what is DNA formed of?
4 types of monomers
nucleotide, consist of two parts: a sugar (deoxyribose) with a phosphate group attached to it, and a base
monomer
what are the four bases?
adenine (A)
guanine (G)
cytosine (C)
thymine (T)
where do cells transcribe portions of their hereditary information
into the same intermediary form (RNA)
2 key classes of polymers
RNA and proteins
DNA to RNA
Transcription
RNA to proteins
Translation
In RNA, what is use instead of thymine
uracil
mass-produced and disposable
RNA transcripts
- guide the synthesis of proteins according to the genetics instructions stored in the DNA.
- intermediates in the transfer of genetic information
mRNA
have distinctive structures that can also give them specialized chemical caopabilities
RNA molecules
may enable RNA to recognize other molecules by binding to them selectively
Shape of RNA molecules
- carry information in the form of a linear sequence of symbols
- a polypeptide
protein
monomer of proteins
amino acids
how is a polypeptide created
by joining its amino acids in a
particular sequence
each protein molecule performing a specific function according to its own genetically specified sequence of ____ ___
amino acids
What does protein catalyze
many chemical reactions
cell-replicating collection of catalysts
A living cell
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
the expression of individual genes is
regulated
regulatory DNA
When the expression of individual genes is regulated, where is it interspersed?
interspersed among the segments that code for protein
What do all cells use as catalyst
Proteins
Each protein is encoded by a ?
Specific 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
A living cell can exist with fewer than ___
genes
500 genes
What are the minimum
requirements in Mycoplasma genitalium
530
genes, about 400 of which are essential
Has 530
genes, about 400 of which
are essential
Mycoplasma genitalium
What is the minimum number of genes far a viable cell
Not less than 300
DNA sequence of any given organism can be readily
obtained by?
biochemical techniques
it is now possible to _________, _____, and ____ any set of living organisms with reference to these sequences.
characterize, catalog, and compare
Cells can be powered by what?
Variety of Free-Energy Sources
feeding
on other living things or the organic chemicals they produce
organotrophic
feeding
on sunlight
Phototrophic
feeding on rock
lithotrophic
produce its own food using light, water, carbon dioxide, or other chemicals.
Autotrophic
eats other plants or animals for energy and nutrients.
Heterotrophic
Different ways of living organisms to obtain their free energy
Organotrophic
Phototrophic
Lithotrophic
Heterotrophic
Autotrophic
Some Cells Fix ____ and ____
____ for Others
Nitrogen and Carbon Dioxide
DNA, RNA, and protein are composed of six elements:
hydrogen
carbon
nitrogen
oxygen
sulfur and
phosphorus
living cells differ widely in some of the most basic aspects of their ___
biochemistry
live mostly as independent individuals or in loosely organized communities, rather than as multicellular
organisms
Prokaryotes
live in an enormous variety of ecological niches, and they are astonishingly varied in their biochemical capabilitiesāfar more so than eukaryotic cells.
Prokaryotic cells
Three primary branches of the tree of life
Bacteria
Archaea and
Eukaryotes
readily interpret such close family resemblances in terms of evolution from common ancestors
Tree of life
prokaryotes comprise two distinct
groups:
Bacteria and Archaea
recently revealed that the first eukaryotic cell formed after a particular type of ancient archaeal cell engulfed an ancient bacterium
detailed genome analyses
What did the detailed genome analyses have recently revealed about the formation of first eukaryotic cell
the first eukaryotic cell formed after a particular type of ancient archaeal cell engulfed an ancient bacterium
The Tree of Life Has Three Primary Branches: Bacteria
- Cyanobacteria
- Bacillus
- E. Coli
- Thermotoga
- Aquifex
The Tree of Life Has Three Primary Branches: Archaea
- Aeropyrum
- Sulfolobus
- Haloferax
- Methano-thermobacter
- Methanococcus
The Tree of Life Has Three Primary Branches: Eukaryotes
- Human
- Maize
- Yeast
- Paramecium
- Dictyostelium
- Euglena
- Trypanosoma
- Giardia
- Trichomonas
may represent a change for the better or cause serious damage
alterations of nucleotide sequence
evolution of organisms
mutations and natural selection
How do genetic specifications changes impact an organismās ability to survive and reproduce
- giving new ways to exploit the environment more effectively
- to survive in competition with others, and to reproduce successfully
What do rapid evolution of certain genes lead to
- new ways to exploit the environment more effectively, resulting for them to survive in competition with others, and to reproduce successfully
Why some genes are highly conserved across species
They perform essential functions that are critical for survival, so changes in these genes are often detrimental
Most Bacteria and Archaea Have ____ā____ Genes
1000ā6000 genes
- can
reproduce the fastest - most can carry very little superfluous
baggage - their genomes are small, with genes packed closely
together and minimal quantities of regulatory DNA
between them
Prokaryotic cells
What do most prokaryotic cells carry
very little superfluous baggage
New Genes Are Generated
from?
Preexisting Genes
Four modes of genetic innovation
- Intragenic mutation
- Gene duplication
- DNA segment shuffling
- Horizontal transfer
Existing genes can be randomly modified by changes in itās DNA sequence
Intragenic mutation
Existing genes can be accidentally duplicated as to create a pair of initially identical genes within a single cell
Gene duplication
2 or more existing genes can break and rejoin to make a hybrid gene consisting of DNA segments that originally belong to separate genomes
DNA segment shuffling
A piece of DNA can be transferred from the genome of one cell to that of another
Horizontal transfer
the transfer of genetic material is from parents to offspring
Vertical gene transfer
genes that are related by descent
Orthologs
related genes that resulted from a gene duplication event
Paralogs
occur much more frequently between different species of prokaryotes
horizontal gene transfers
have a remarkable capacity to take up even nonviral DNA molecules from surroundings, and thereby capture the genetic information
bacteriophages
Sex Results in ____ Exchanges of Genetic Information
Within a Species
Horizontal
causes a large-scale horizontal transfer of genetic information between two initially separate cell lineagesā
those of the father and the mother
sexual reproduction
determines gene function
gene sequence
What are the two complementary approaches where analysis of gene functions depends on
genetics and biochemistry.
study of mutant
genetics
function of molecules
biochemistry
Molecular Biology Began with a Spotlight on ____
E. coli
- small, rod-
shaped bacteria
ā¢ grown easily on simple nutrient broth
ā¢ adapts to variable chemical conditions and reproduces
rapidly
ā¢ evolve by mutation and selection at a remarkable
speed
Escherichia coli
bigger and more elaborate than prokaryotic cells, and their genomes are bigger and more elaborate, too.
Eukaryotic cells
the way of life of a ___ cell that was a
predator, living by capturing other cells and
eating them
primordial
eukaryotic cells are 10 times bigger in __ dimension and 1000 times larger in __
linear
volume
helps cells maintain their shape and internal organization, and it also provides mechanical support that enables cells to carry out essential functions like division and movement.
Cytoskeleton
It is now generally accepted that mitochondria originated from ____-_____ _____-______ bacteria that were engulfed by an ancestral cell that could otherwise make no such use of oxygen (that is, was anaerobic).
free-living oxygen-metabolizing (aerobic)
first eukaryotic cells formed after an archaeal cell engulfed an ___ bacterium
aerobic
have their own genome; originated as symbiotic photosynthetic bacteria
mitochondria and chloroplasts
provides energy to eukaryotic cells
chloroplast
plant cells lost the ability to do _____ having a tough, protective cell wall
phagocytosis
possesses mitochondria and have a tough outer wall
fungi
the genomes of most ___ have become orders of magnitude larger than those of bacteria and archaea
Eukaryotes
___% of human genome do not code for proteins
~98.5%
__% in E.coli do not code for protein
11%
regulate the expression of adjacent genes
regulatory DNA
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
Example of Solitary eukaryotic Cells
ā¢ protozoa (hunters)
ā¢ unicellular algae (photosynthesizer)
ā¢ unicellular fungi or yeast (scavengers)
ā¢ small, single-celled; closely related to animals as it is to
plants
ā¢ robust and easy to grow in a simple nutrient medium
ā¢ reproduce vegetatively (budding)
Saccharomyces cerevisiae (yeast)
Has Been Chosen Out of 300,000 Species As a Model Plant
Arabidopsis
ā¢ can be grown indoors
ā¢ produces thousands of offspring per plant after 8-10weeks
ā¢ genome size of approx. 220 million nucleotide pairs
Thale cress (Arabidopsis
thaliana)
The World of Animal Cells Is Represented By
Worm, Fly, Fish, Mouse, and Human
model organisms for molecular genetic studies
ā¢ nematode worm Caenorhabditis
elegans
ā¢ the fly Drosophila melanogaster
ā¢ the zebrafish Danio rerio
ā¢ the mouse Mus musculus
ā¢ the human, Homo sapiens
ā¢ model genetic organism
ā¢ definitive proof that genes are
carried on chromosomes
ā¢ 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
fruit fly Drosophila
melanogaster
almost every gene in the vertebrate genome has
Paralogs
do occur from time to time in evolution
whole-genome duplications
Provide a Key to Vertebrate Development
Studies in Drosophila
a Product of Repeated Duplications
Vertebrate Genome
with ordinary diploid genome
X. tropicalis
duplicated genome
X. laevis
Provide Accessible Models for
Vertebrate Development
Frog and the Zebrafish
-embryonic development
ā¢ eggs are big, easy to manipulate, fertilized outside
the animal
frogs
compact genome, generation time of 3 months, many mutants are known, and genetic engineering is relatively
easy
zebrafish
ā¢ are highly uniform group of organisms
ā¢ species resemble one another genetically
Mammals (mammalian species)
human and elephant = __% of amino acids are identical
85%
human and bird = ___% similarity
70%
the
Predominant
Mammalian Model
Organism
Mouse
- foremost model organism for experimental studies of
vertebrate molecular genetics - many naturally occurring mutations are known, often
mimicking the effects of corresponding mutations in
humans
Mouse
Humans Report on Their Own ___
Peculiarities
Humans catalog their own ___ _____
genetic disorders
Human inheritance and genetic disorders
Polydactyly
Hypertrichosis
Progeria
Hemophelia
Down syndrome
Sickle cell anemia
mitochondria and chloroplasts originated as?
symbiotic photosynthetic
bacteria
ā¢ 4300 approx. number of genes
ā¢ 4.6 x10ā¶ genome size (nucleotide pairs)
Escherichia coli (bacterium)
ā¢ 4300 approx. number of genes
ā¢ 4.6 x10ā¶ genome size (nucleotide pairs)
Escherichia coli (bacterium)
- 6600 approx. number of genes
- 13 x 10ā¶ genome size
Saccharomyces cerevisiae(yeast)
- 21,000 approx number of genes
- 130 x 10ā¶ genome size
Caenorhabditis elegans (roundworm)
- 29,000 approx number of genes
- 220 x 10ā¶ genome size
Arabidopsis thaliana (plant)
- 15,000 approx. number of genes
- 200 x 10ā¶ genome size
Drosophila melanogaster (fruit fly)
- 32,000 approx. number of genes
- 1400 x 10ā¶ genome size
Danio rerio (zebrafish)
- 30,000 approx number of genes
- 2800 x 10ā¶ genome size
Mus musculus (mouse)
- 30,000 approx. number of genes
- 3200 x 10ā¶ genome size
Homo sapiens
Includes an estimate for the amount of highly repeated DNA sequence, not in genome databases
Genome size
Collaborate to reproduce the entire collection before a cell divides
Cellās collection of catalyst
- shows the evolutionary relationships among diff. organisms
- like a family tree
Phylogenetic tree
Show where genetic or physical similarities and difference between organisms begin or end
Branch
Represents a distant ancestor of the species that appear at the ends of the branches
Root
- where branches separate
- points where ancestral lines split into new lines of evolution
Nodes
example of spherical cells
streptococcus
Example of rod-shaped cells
Escherichia coli and vibrio cholerae
the smallest cells
Mycoplasma spiroplasma
Example of spiral cells
Treponema pallidum