Module 1A Cells and Genomes Flashcards
the study of the structure, function, and behavior of cells.
Cell biology
Who said, “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
What fundamental similarity exists among living organisms despite their diversity?
living things are fundamentally similar inside
distinguishes life from other processes, as it involves a link between the characteristics of parents and their offspring.
heredity
Where do all living cells on Earth store their hereditary information?
double-stranded molecules of DNA
double-stranded molecules which are long, unbranched, paired polymer chains made of the same four types of monomers.
Deoxyribonucleic acid (DNA)
What is the process by which all cells replicate their hereditary information?
templated polymerization using double-stranded DNA molecules
A __ is the monomer of DNA, consisting of a sugar (deoxyribose) with a phosphate group attached and a nitrogenous base.
nucleotide
A nucleotide is the monomer of DNA, consisting of a __(__) with a __ attached and a __.
- sugar (deoxyribose)
- phosphate group
- nitrogenous base
What are the four bases found in DNA? (4)
- adenine (A)
- guanine (G)
- cytosine (C)
- thymine (T)
- transcribes portions of hereditary information from DNA and serves as an intermediary in the transfer of genetic information, guiding the synthesis of proteins.
- molecules can have unique shapes that enable them to recognize and bind to other molecules selectively.
Ribonucleic acid (RNA)
RNA contains ribose sugar and __(_) instead of thymine (T) found in DNA. __ are mass-produced, disposable intermediates.
- uracil (U)
- RNA transcripts
What are the two main processes involved in the expression of DNA information? (2)
- transcription (DNA to RNA)
- translation (RNA to proteins).
- act as catalysts that facilitate and accelerate chemical reactions in cells.
- carry information in the form of a linear sequence of symbols, which corresponds to their amino acid sequence.
proteins
The monomer of proteins is the __, of which there are __ different types.
- amino acid
- 20
- a protein molecule created by joining amino acids in a specific sequence.
- chains of amino acids linked by peptide bonds.
- a long, continuous, unbranched peptide chain.
polypeptide
a living cell contains various proteins that catalyze chemical reactions necessary for its __ and __ processes.
- replication
- metabolic
a segment of DNA sequence that corresponds to a single protein, a set of alternative protein variants, or a single catalytic regulatory, or structural RNA molecule.
gene
Each protein is encoded by a specific __, which determines the protein’s amino acid sequence and, consequently, its function.
gene
The expression of individual genes is regulated by __ sequences that are interspersed among the segments that code for proteins.
regulatory DNA
What types of molecules can a gene correspond to besides proteins? (2)
- catalytic regulatory RNAs
- structural RNAs.
The __ encloses each cell and acts as a selective barrier, regulating the passage of nutrients and waste materials.
plasma membrane
The plasma membrane is __, consisting of both hydrophobic (water-insoluble) and hydrophilic (water-soluble) parts, creating a bilayer.
amphiphilic
largely determine which molecules can enter or exit the cell, facilitating selective transport across the plasma membrane.
Membrane transport proteins
What is the minimum number of genes required for a viable cell to exist?
Not less than 300 genes.
- Which organism is known for having one of the smallest genomes with around 530 genes?
- Out of these genes, how many are considered essential?
- Mycoplasma genitalium
- Approximately 400 genes.
How can scientists characterize, catalog, and compare organisms today?
analyzing DNA sequence through standard biochemical techniques.
A cell that feeds on organic chemicals from other living organisms.
organotrophic
A cell that feeds on sunlight for energy.
phototrophic
A cell that feeds on rock or inorganic substrates
lithotrophic
Which six elements make up DNA, RNA, and proteins? (6)
- Hydrogen
- carbon
- nitrogen
- oxygen
- sulfur
- phosphorus.
Do eukaryotic or prokaryotic cells show greater biochemical diversity?
Prokaryotic cells
How do prokaryotic cells usually live?
As independent individuals or in loosely organized communities.
cells that can live in an enormous variety of ecological niches.
prokaryotic cells
What are the three primary branches of the Tree of Life? (3)
Bacteria, Archaea, and Eukaryotes.
What are the two distinct groups within prokaryotes?
Bacteria and Archaea.
How was the first eukaryotic cell thought to have formed?
An ancient archaeal cell engulfed an ancient bacterium.
How can the close family resemblances among organisms be interpreted?
In terms of evolution from common ancestors.
Process that may represent beneficial changes or cause serious damage.
genetic level
alterations of nucleotide sequence
What drives the evolution of organisms? (2)
Mutations and natural selection.
Provides organisms new ways to exploit the environment more effectively, to survive in competition with others, and to reproduce successfully
evolutionary adaptations
genetic specifications changes
How many genes do most bacteria and archaea have?
Between 1,000 and 6,000 genes.
What cells have small genomes with closely packed genes and minimal regulatory DNA? This is why they reproduce __.
- Prokrayotic cells
- the fastest
What are the four modes of genetic innovation? (4)
1) Intragenic mutation
2) Gene duplication
3) DNA segment shuffling
4) Horizontal transfer
Within a single cell, what could lead to families of related genes?
Gene duplications
When a part of the genome is duplicated inappropriately, it can lead to __, which may result in __.
new..while retaining some of the original gene’s characteristics.
- gene duplication
- gene families
- copy number variations
Two types of gene homology based on different evolutionary pathways (2)
orthologs and paralogs
- Genes related by descent from a common ancestor.
- Speciation
orthologs
Genes that are related due to a gene duplication event.
- Divergence
paralogs
The transfer of genes between organisms, often occurring more frequently between different species of prokaryotes.
horizontal gene transfer
Give an example of horizontal gene transfer.
Bacteriophages can transfer genetic information between bacteria.
Prokaryotes capture genetic information from their surroundings. They have a remarkable capacity to take up __.
nonviral DNA molecules
A large-scale horizontal transfer of genetic information between two initially separate cell lineages—those of the father and mother.
Sexual reproduction
How can the function of a gene often be deduced?
By analyzing its sequence, which often indicates it is similar to that of already known homologs.
How many gene families are common to all three primary branches of the Tree of Life?
More than 200 gene families.
What are the two complementary approaches for analyzing gene functions? (2)
- Genetics, which studies mutants
- biochemistry, which studies the function of molecules.
- A small, rod-shaped bacterium that can be easily grown on simple nutrient broth.
- It adapts to variable chemical conditions and reproduces rapidly.
- It evolves by mutation and selection at a remarkable speed.
Escherichia coli (E. coli)
__ cells are generally bigger and more elaborate than __ cells, with larger and more complex genomes.
- Eukaryotic
- prokaryotic
How much larger are eukaryotic cells compared to prokaryotic cells? (in linear dimension and volume)
Eukaryotic cells are 10 times bigger in linear dimension and 1000 times larger in volume.
What structural feature is present in eukaryotic cells that aids in maintaining their shape?
cytoskeleton
How did primordial eukaryotic cells obtain their nutrition?
They lived as predators, capturing and consuming other cells.
An organelle that originated from free-living aerobic bacteria that were engulfed by an ancestral anaerobic cell.
Mitochondria
The first eukaryotic cells were formed after an __ engulfed an __.
- archaeal cell
- aerobic bacterium
What is unique about the genomes of mitochondria and chloroplasts?
They have their own genomes and originated from symbiotic photosynthetic bacteria.
What role does the chloroplast play in eukaryotic cells?
- provides energy
– synthesise food by the process of photosynthesis.
Why did plant cells lose the ability to perform phagocytosis?
due to having a tough, protective cell wall.
Do fungi possess mitochondria, and what is their cell structure like?
Yes, fungi possess mitochondria and have a tough outer wall.
The genomes of most eukaryotes are orders of magnitude larger than those of __ and __.
- bacteria
- archaea
What percentage of the human genome does not code for proteins?
~98.5%
How much noncoding DNA is present in E. coli’s genome?
11%
What type of DNA is more abundant in eukaryotic genomes compared to coding DNA?
Regulatory DNA
What regulates the expression of adjacent genes?
Regulatory DNA
What specifies the program of multicellular development; the extraordinary variation of cells in an individual animal or plant?
Definition: the complete set of genetic material (DNA or RNA) in an organism, including all of its genes and non-coding sequences.
Genome
bind to regulatory DNA adjacent to genes to control their expression, or they interfere with the abilities of other proteins to regulate gene expression.
Transcription regulators
What are some examples of unicellular eukaryotes? (3)
- protozoa (hunters)
- unicellular algae (photosynthesizers)
- unicellular fungi or yeast (scavengers)
How do unicellular eukaryotes compare in diversity to multicellular organisms?
far more diverse
- A minimal model eukaryote; a simple organism used for studying eukaryotic biology. Which organism serves as the minimal model eukaryote?
- small, single-celled, closely related to both animals and plants, robust, easy to grow in a simple nutrient medium, and reproduces vegetatively (budding).
Saccharomyces cerevisiae (yeast)
What are the characteristics of yeast? (4)
- small, single-celled
- closely related to both animals and plants
- robust, easy to grow in a simple nutrient medium
- reproduces vegetatively (budding).
Which plant has been chosen as a model plant, and what is its scientific name?
- thale cress
- Arabidopsis thaliana
Arabidopsis thaliana can be grown __ and produces __ of offspring per plant after __ weeks.
- indoors
- thousands
- 8-10
What is the approximate genome size of Arabidopsis thaliana? (How many nucleotide pairs?)
~ 220 million nucleotide pairs
Which organisms are model organisms for molecular genetic studies? (5)
- Worm - Caenorhabditis elegans
- Fly - Drosophila melanogaster
- Fish - Danio rerio (zebrafish)
- Mouse - Mus musculus
- Human - Homo sapiens (humans)
a model genetic organism that provides definitive proof that genes are carried on chromosomes and helps trace the chain of cause and effect from genetic instructions to the structure of the adult multicellular body.
Drosophila melanogaster (fruit fly)
The vertebrate genome is characterized by almost every gene having __ due to repeated duplications.
paralogs
Duplications that occur from time to time in evolution, and contribute to the complexity of vertebrate genomes.
Whole-genome duplications
Which frog genus is mentioned as having different genome types–one with an ordinary diploid genome and one with a duplicated genome (tetraploid)?
- These are widely used in biological research, particularly in developmental biology and genetics.
The frog genus Xenopus
- X. tropicalis - with an ordinary diploid genome
- X. laevis - with a duplicated genome.
are large, easy to manipulate, and fertilized outside the animal, making them suitable for studying embryonic development.
frog eggs
an organism that have a compact genome, a generation time of 3 months, many known mutants, and genetic engineering is relatively easy.
zebrafish
The leading model organism for vertebrate molecular genetics because mammals are genetically similar, and many naturally occurring mutations in this organism mimic effects seen in humans.
mouse
How genetically similar are humans to elephants and birds?
Humans and elephants share 85% of amino acids, while humans and birds share 70%.
What is one way humans report on their own peculiarities?
We catalog our own genetic disorders.
What are some examples of genetic disorders cataloged in humans? (6)
- Polydactyly (extra digits)
- hypertrichosis (excessive hair growth)
- progeria (rapid aging)
- hemophilia (disorder in blod clot)
- Down syndrome (extra copy of chromosome 21)
- sickle cell anemia (rbc is sickle-shaped)
