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biology > genetic infortmation and variation and relationships between organisms > Flashcards

genetic infortmation and variation and relationships between organisms Flashcards

1
Q

What is the structure of eukaryotic DNA?

A

Linear, long molecule associated with histone proteins, coiled into chromosomes

Eukaryotic DNA is found in the nucleus and is tightly coiled to fit within it.

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2
Q

Where is prokaryotic DNA located?

A

Found freely in the cytoplasm within a region called the nucleoid

Prokaryotic DNA is a single, circular chromosomal DNA molecule and is not associated with histone proteins.

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3
Q

What are plasmids?

A

Very small circular DNA molecules that usually contain a few genes

Plasmids are important for gene expression and often carry genes for antibiotic resistance.

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4
Q

What is a gene?

A

A section of DNA that contains a sequence of DNA bases coding for a polypeptide or functional RNA

A gene occupies a specific fixed position called a locus on a particular DNA molecule.

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5
Q

Define allele.

A

An alternative form of a gene

An individual inherits one allele from each parent, which can be the same or different.

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6
Q

What is the genome?

A

The complete set of DNA in an organism

The full genome is present in every cell, but not every gene is expressed in every cell.

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7
Q

What is the proteome?

A

The full range of proteins that a cell is able to produce

The proteome is usually larger than the genome due to post-translational modifications and alternative splicing.

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8
Q

What are the features of the genetic code?

A

Non-overlapping, degenerate, universal

Non-overlapping means triplets don’t share bases; degenerate means more triplets than amino acids; universal means the same triplets code for the same amino acids in all organisms.

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9
Q

Differentiate between introns and exons.

A

Introns do not code for amino acids, while exons do code for amino acids

Introns are removed during splicing in eukaryotic cells.

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10
Q

What are homologous chromosomes?

A

A pair of matching chromosomes, one maternal and one paternal

Humans have 23 pairs of chromosomes, totaling 46, which is the diploid number.

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11
Q

What is the primary role of mRNA?

A

Carries the genetic code from DNA to ribosomes for protein synthesis

mRNA is made during transcription and is a single-stranded polymer of RNA.

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12
Q

What is transcription?

A

The process of making pre-mRNA using part of the DNA as a template

It involves breaking hydrogen bonds between DNA bases and aligning free RNA nucleotides.

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13
Q

What happens during translation?

A

A polypeptide chain is formed by the ribosome using mRNA

tRNA molecules bring specific amino acids that are linked together to form a protein.

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14
Q

What is a mutation?

A

Any change to the quantity or base sequence of the DNA of an organism

Gene mutations can arise spontaneously during DNA replication.

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15
Q

What is base deletion?

A

When a nucleotide is lost from the normal DNA sequence

It causes a frameshift, altering the reading of all subsequent triplets.

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16
Q

What is base substitution?

A

When a nucleotide in a DNA molecule is replaced by another nucleotide

This can result in a polypeptide that differs by a single amino acid.

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17
Q

What is the significance of introns in eukaryotic DNA?

A

They are removed during splicing and do not code for amino acids

Their exact purpose is not fully understood.

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18
Q

What is the role of tRNA in protein synthesis?

A

Carries amino acids to ribosomes and has an anticodon for pairing with mRNA codons

Each tRNA is specific to one amino acid.

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19
Q

Fill in the blank: The genetic code is made up of sequences of _______.

A

base triplets (codons)

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20
Q

What is a substitution mutation?

A

A nucleotide in a DNA molecule is replaced by another nucleotide that has a different base.

The polypeptide produced will differ in a single amino acid.

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21
Q

What is the consequence of a deletion mutation?

A

It causes a frameshift, changing the sequence of codons on mRNA and altering the sequence of amino acids in the primary structure of a polypeptide.

This can affect the tertiary structure of the protein, potentially rendering it unable to function.

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22
Q

What is a nonsense mutation?

A

A mutation that changes the base sequence to code for a stop codon, resulting in a shortened polypeptide chain.

This prevents the protein from folding correctly and functioning.

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23
Q

What is a missense mutation?

A

A mutation that changes the base sequence to code for a new amino acid, potentially affecting the protein’s tertiary structure.

This can impair the protein’s function, especially if it’s an enzyme.

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24
Q

What is a silent mutation?

A

A mutation that changes the base sequence but does not alter the amino acid coded for, or occurs in an intron.

This is due to the degeneracy of the genetic code.

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25
What are mutagenic agents?
Agents that increase the rate of gene mutation beyond the naturally occurring mutation rate. ## Footnote Examples include high energy radiation, ultraviolet light, and alpha particles.
26
What is the diploid number of chromosomes in humans?
46 ## Footnote Diploid cells have two of each chromosome, one set from each parent.
27
What is the haploid number of chromosomes in humans?
23 ## Footnote Haploid cells contain one copy of each chromosome in a homologous pair.
28
What are gametes?
Sex cells that contain a haploid number (n) of chromosomes, which is 23 in humans. ## Footnote Gametes are sperm in males and eggs in females, all genetically different.
29
What is meiosis?
A type of cell division that forms gametes, starting as diploid and ending as haploid through two divisions. ## Footnote It involves the separation of homologous pairs and chromatids.
30
What happens during prophase I of meiosis?
Homologous chromosomes form bivalents, undergo crossing over at chiasmata, and exchange equivalent portions. ## Footnote This results in new genetic combinations.
31
What is independent segregation in meiosis?
The random orientation and separation of homologous pairs during metaphase I, leading to genetic variation. ## Footnote It determines which parent chromosome ends up in the daughter cells.
32
What is the outcome of meiosis?
Four genetically different haploid gametes are produced. ## Footnote Each gamete contains 23 chromosomes.
33
What is a genetic bottleneck?
An event that causes a significant reduction in a population, leading to decreased genetic diversity. ## Footnote Survivors reproduce, creating a population from a smaller gene pool.
34
What is the founder effect?
When a small group of organisms establishes a new population, resulting in reduced genetic variation. ## Footnote This can lead to a higher chance of genetic diseases.
35
What is natural selection?
The process by which advantageous alleles increase in frequency in a population, leading to evolution. ## Footnote It occurs when individuals with beneficial traits are more likely to survive and reproduce.
36
How does meiosis contribute to genetic diversity?
Through crossing over, independent segregation, and random fertilization. ## Footnote These processes create new combinations of alleles.
37
What is aneuploidy?
When an organism has an extra copy of just one individual chromosome. ## Footnote This can lead to genetic diseases such as Down syndrome.
38
What are the consequences of chromosome non-disjunction?
Changes in the number of chromosomes, leading to conditions like polyploidy or aneuploidy. ## Footnote This results from failure of homologous pairs or chromatids to separate.
39
What is the formula to calculate the number of different combinations of chromosomes in daughter cells after meiosis?
2^n ## Footnote Where n is the number of homologous pairs.
40
What is genetic drift?
The change in frequency of an existing gene variant in a population due to random chance. ## Footnote It can reduce genetic variation by causing some gene variants to disappear.
41
What is the significance of genetic diversity?
Increases the likelihood that some individuals in a population will survive environmental changes. ## Footnote This allows populations to adapt and is crucial for natural selection.
42
What is competition in the context of natural selection?
Competition with others increases the likelihood of obtaining resources, leading to growth and longevity. ## Footnote This competition affects breeding success and offspring production.
43
What does it mean to reproduce successfully?
Only those individuals that reproduce successfully pass on their alleles to the next generation.
44
What happens to the frequency of beneficial alleles over generations?
The frequency of beneficial alleles increases while less advantageous alleles decrease. ## Footnote This leads to evolution as advantageous alleles become more common.
45
Define adaptations.
Adaptations are characteristics that enhance an organism's chance of survival and reproduction.
46
What are behavioral adaptations?
Ways an organism acts that increase its chance of survival. ## Footnote Examples include playing dead, migration, and mating dances.
47
What are physiological adaptations?
Processes inside an organism’s body that enhance survival. ## Footnote Examples include hibernation and antibiotic production by bacteria.
48
What are anatomical adaptations?
Structural features of an organism’s body that increase survival. ## Footnote Examples include camouflage in polar bears and streamlined shapes in otters.
49
What is selection in evolutionary biology?
Selection occurs when better adapted organisms survive to breed, while less well-adapted organisms do not.
50
What is directional selection?
A type of selection where one extreme phenotype is favored, leading to changes in the mean phenotype of the population.
51
Provide an example of directional selection.
Bacteria evolving antibiotic resistance.
52
What is stabilizing selection?
A type of selection where the average phenotype is favored, reducing the range of possible characteristics.
53
Give an example of stabilizing selection.
Human birth weight, where medium-sized babies have higher survival rates.
54
Define species.
A group of organisms that share similar characteristics and can interbreed to produce fertile offspring.
55
What is phylogenetics?
The study of evolutionary relationships between organisms.
56
What is classification in biology?
The grouping of organisms based on shared characteristics.
57
What does binomial nomenclature refer to?
A universal system for naming organisms using two names: the genus and the species.
58
What is the importance of courtship behavior?
It helps ensure mating occurs between the same species, facilitating reproduction and survival of the species.
59
What is a stimulus response chain?
A sequence of actions that helps individuals identify potential mates of the same species.
60
What is a phylogenetic tree?
A diagram representing the evolutionary relationships among different species.
61
What role does taxonomy play in biology?
Taxonomy is the science of classification of organisms into hierarchical groups.
62
What are homologous characteristics?
Features that have similar evolutionary origins, regardless of their functions. ## Footnote Examples include the wings of birds and the arms of humans.
63
What is biodiversity?
The variety and amount of living organisms in an area.
64
List the three components of biodiversity.
* Species diversity * Genetic diversity * Ecosystem diversity
65
How does biodiversity relate to ecosystem stability?
Higher species diversity usually leads to more stable ecosystems.
66
What is the significance of genome sequencing?
It allows for the comparison of DNA base sequences between species to determine evolutionary relationships.
67
What do immunological comparisons reveal about evolutionary relationships?
Similar proteins will bind the same antibodies, indicating relatedness among species.
68
What is the species diversity index?
A measure of the variety of species in a community, indicating stability and resilience to changes.
69
How does a high species diversity index affect a community during a drought?
Increases the likelihood that at least one species can tolerate drought, allowing for survival and community maintenance.
70
What is species richness?
The number of different species in a particular area at a given time.
71
True or False: Species richness takes into account the population sizes of species.
False
72
What is the index of diversity?
Describes the relationship between the number of species in a community and the number of individuals in each species.
73
What does a higher index of diversity indicate?
A more diverse community.
74
What happens to biodiversity in extreme environments, such as hot deserts?
The species diversity index is normally low, leading to an unstable ecosystem dominated by climatic factors.
75
Fill in the blank: As natural ecosystems develop, they become __________ communities.
[complex]
76
What impact does agriculture have on species diversity?
It reduces species diversity and lowers the index of species diversity.
77
What is one consequence of woodland clearance for agriculture?
It directly reduces the number of trees and tree species, destroying habitats.
78
What effect do pesticides have on biodiversity?
They kill pests, which can lead to a decrease in species that feed on those pests.
79
Define monoculture in agriculture.
The cultivation of a single crop species over a wide area.
80
What is the purpose of conservation schemes?
To protect endangered species and create protected areas to restrict development.
81
What does genetic diversity refer to?
The total number of different alleles of genes in a species or population.
82
How is genetic diversity measured today?
By comparing DNA, mRNA, and amino acid sequences.
83
What is the relationship between DNA sequence similarity and evolutionary relationships?
Species with more similar DNA are more closely related.
84
True or False: Observable characteristics are solely determined by environmental factors.
False
85
What limitations exist when using observable characteristics to classify organisms?
Many characteristics are polygenic and influenced by environmental factors.
86
How does comparing amino acid sequences help in understanding genetic diversity?
It reflects how closely related two species are based on the similarity in their protein structures.
87
What is the expected outcome of speciation on DNA sequences?
New species will initially have similar DNA, but mutations will cause divergence over time.
88
Fill in the blank: The balance between farming and __________ is essential for maintaining biodiversity.
[conservation]
89
What is the result of overgrazing on land regeneration?
It prevents regeneration of land.
90
What does a Spearman’s rank correlation test measure?
The correlation between two variables.

biology (10 decks)

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