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Biology > Genetic infomation, variation and relationships between organisms > Flashcards

Genetic infomation, variation and relationships between organisms Flashcards

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1
Q

What are the two key similarities between eukaryotic and prokaryotic DNA?

A

Both are made up of DNA nucleotides and are joined together by phosphodiester bonds

The nucleotides contain deoxyribose, a phosphate group, and a nitrogenous base.

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2
Q

What are the three key differences between eukaryotic and prokaryotic DNA?

A
  • Eukaryotic DNA is longer
  • Eukaryotic DNA is linear
  • Eukaryotic DNA is associated with histones, while prokaryotic DNA is not

Eukaryotic DNA occurs as straight lines in chromosomes, while prokaryotic DNA forms circular loops.

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3
Q

What is the structure of DNA in eukaryotic cells?

A

DNA is tightly coiled into chromosomes within the nucleus, and forms nucleosomes by wrapping around histone proteins

This organization allows DNA to fit within the nucleus.

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4
Q

How does the DNA in mitochondria and chloroplasts compare to prokaryotic DNA?

A

Both have short sequences of circular DNA that are not wrapped around histone proteins

They have their own DNA to transcribe and translate enzymes necessary for photosynthesis (chloroplasts) and respiration (mitochondria).

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5
Q

Define a gene.

A

A sequence of DNA that codes for the amino acid sequence of a polypeptide and functional RNA

It also codes for an mRNA molecule.

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6
Q

What is a locus?

A

The exact position of a particular gene on a chromosome

‘Locus’ can be remembered as ‘location’.

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7
Q

What is a triplet in the context of DNA?

A

A sequence of three bases on DNA that codes for a particular amino acid

Triplets are essential for understanding the genetic code.

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8
Q

List the three main features of the genetic code.

A
  • Degenerate
  • Universal
  • Non-overlapping

The degenerate feature means multiple triplets can code for the same amino acid.

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9
Q

Explain what is meant by the genetic code being degenerate.

A

There are more than one triplet of bases that codes for the same amino acid

For example, glycine can be coded by GGG, GGA, GGC, and GGU.

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10
Q

What does it mean for the genetic code to be universal?

A

The same triplet of bases codes for the same amino acid in all organisms

This consistency is important for the evolutionary connection among species.

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11
Q

What does non-overlapping mean in the genetic code?

A

Each base is only involved in one triplet, and codons are read as discrete units

This minimizes the impact of mutations.

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12
Q

Differentiate between introns and exons.

A
  • Introns: Sequences of DNA bases that do not code for polypeptides
  • Exons: Sequences of DNA bases that do code for amino acids

Exons are the coding regions of a gene.

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13
Q

What is a codon?

A

Three bases on mRNA that code for a specific amino acid

The start codon initiates translation, while stop codons signal the end.

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14
Q

Define a genome.

A

An organism’s complete set of genes in a cell

This includes all genetic material of the organism.

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15
Q

What is a proteome?

A

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

The proteome can change depending on the proteins needed by the cell.

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16
Q

How does the genome of bacteria compare to that of humans?

A

Bacteria have an average of 600,000 DNA base pairs, while humans have about three billion

This illustrates the vast differences in genomic complexity.

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17
Q

What is messenger RNA (mRNA)?

A

A short, single-stranded copy of one gene, found in both the cytoplasm and nucleus

It is created during transcription.

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18
Q

What is the role of transfer RNA (tRNA)?

A

tRNA carries specific amino acids to the ribosome during translation

It has an anticodon that is complementary to the mRNA codon.

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19
Q

Explain the process of transcription.

A

A complementary mRNA copy of one gene is created from DNA in the nucleus

Key steps include unwinding DNA, aligning RNA nucleotides, and splicing out introns.

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20
Q

What happens during translation?

A

mRNA binds with a ribosome, and tRNA brings amino acids to form a polypeptide chain

This process continues until a stop codon is reached.

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21
Q

What is the role of the Golgi body in protein synthesis?

A

It modifies the polypeptide chain into its functional structure

This includes folding into secondary, tertiary, or quaternary structures.

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22
Q

What is a gene mutation?

A

A change in the base sequence of DNA that occurs randomly during DNA replication

Mutations can be influenced by exposure to mutagenic agents.

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23
Q

What is a gene mutation?

A

A change in the base sequence of DNA that occurs randomly during DNA replication.

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24
Q

What are mutagenic agents?

Study These Flashcards
A

Agents that can interfere with DNA replication, increasing the likelihood of mutations. Examples include:
* High energy radiation (UV light, gamma rays, x-rays)
* Chemicals (carcinogens like mustard gas and cigarette smoke)

25
What is a base mutation?
A mutation that may have no impact if the new codon still codes for the same amino acid due to the degeneracy of the genetic code.
26
What are chromosome mutations?
Changes in the number of chromosomes that can occur spontaneously during meiosis.
27
Define non-disjunction.
A failure of chromosomes or chromatids to equally split during anaphase of meiosis I or meiosis II.
28
What is polyploidy?
A change in the whole sets of chromosomes, resulting in organisms with more than two sets of chromosomes (e.g., triploid or tetraploid).
29
What is aneuploidy?
Changes in the number of individual chromosomes, often resulting from non-disjunction.
30
What is Down syndrome?
A condition caused by non-disjunction of chromosome 21, resulting in three copies of that chromosome.
31
What is the result of meiosis?
The creation of four genetically different haploid gametes through two nuclear divisions.
32
What are the two mechanisms of genetic variation in meiosis?
1. Independent segregation of homologous chromosomes 2. Crossing over between homologous chromosomes
33
What is independent segregation?
The random alignment of homologous pairs at the equator during meiosis, leading to a variety of chromosome combinations in daughter cells.
34
How is genetic diversity calculated from independent segregation?
Using the formula 2^n, where n is the number of homologous pairs of chromosomes.
35
What is crossing over?
The exchange of genetic material between homologous chromosomes during meiosis, creating new combinations of alleles.
36
How does meiosis differ from mitosis?
Meiosis involves two nuclear divisions and produces haploid cells, while mitosis involves one nuclear division and produces diploid cells.
37
What is genetic diversity?
The number of different alleles of genes in a population, enabling natural selection.
38
What is natural selection?
The process that leads to evolution, defined as the change in allele frequency over generations.
39
What is directional selection?
A type of selection where an advantageous allele codes for an extreme trait, such as antibiotic resistance in bacteria.
40
What is stabilizing selection?
A type of selection where the average trait remains advantageous, exemplified by optimal human birth weights.
41
What defines a species?
A group of organisms that can produce fertile offspring.
42
What is courtship behavior?
A sequence of actions unique to each species that helps identify members of the same species for reproduction.
43
What is courtship behavior?
A sequence of actions unique to each species, essential for successful mating and creating fertile offspring ## Footnote Courtship behavior is genetically coded and helps animals identify members of their own species.
44
Who typically carries out the courtship behavior?
Normally carried out by the male ## Footnote The female then decides if the male is worthy of mating based on observed behaviors.
45
What are some components of courtship behavior?
Dance moves, creation of sounds, release of pheromones, display of feathers, fighting ## Footnote These components help in species recognition and mate selection.
46
Why is courtship behavior important for reproduction?
Ensures successful reproduction by recognizing species and synchronizing mating behavior ## Footnote It helps ensure that males and females mate when they are sexually mature.
47
What is a pair bond?
A strong bond formed between parents during courtship, increasing offspring survival ## Footnote This bond is crucial in species like penguins for chick care.
48
How can courtship behavior be used in phylogenetic classification?
To identify how closely related different species are based on similarities in courtship rituals ## Footnote Similar behaviors suggest closer genetic relationships.
49
What is phylogenetic classification?
Arranging groups according to evolutionary origins and relationships ## Footnote It helps visualize the evolutionary tree and relationships among species.
50
What is the significance of the recent common ancestor in phylogenetic classification?
Species that branched off more recently have had less time to accumulate mutations ## Footnote This indicates closer genetic relationships, as seen between humans and chimpanzees.
51
What is a hierarchy in biological classification?
Smaller groups arranged within larger groups without overlap ## Footnote The hierarchy includes domain, kingdom, phylum, class, order, family, genus, and species.
52
What does the binomial system refer to?
A universal way of identifying organisms using two names: genus and species ## Footnote Example: Humans are classified as Homo sapiens.
53
What is biodiversity?
The variety of life in a particular habitat or ecosystem ## Footnote It can be measured in terms of species richness, genetic diversity, and habitat variety.
54
What does species richness mean?
The number of different species in a community ## Footnote It is a key component of species diversity.
55
What can indicate a low biodiversity in certain habitats?
Expected low biodiversity in Arctic regions or deserts ## Footnote A decrease in biodiversity, however, is a concern and may result from human activities.
56
What is the index of diversity?
A measure describing the relationship between the number of species and the number of individuals within each species ## Footnote A higher value indicates greater biodiversity.
57
What is the formula for calculating the index of diversity?
D = (N(N-1))/Σ(n(n-1)) ## Footnote N is total number of organisms, n is population size of one species.
58
What are some methods to measure genetic diversity?
Comparing observable characteristics, DNA sequences, mRNA sequences, or amino acid sequences ## Footnote DNA-based comparisons are more accurate than observable characteristics.

Biology (6 decks)

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