Topic 4: Genetic information, variation and relationships between organisms

What carries genetic information in cells?

DNA carries genetic information, while RNA transfers it.

What are the components of a DNA nucleotide?

Deoxyribose, a phosphate group, and one of the organic bases: adenine, cytosine, guanine, or thymine.

What are the components of an RNA nucleotide?

Ribose, a phosphate group, and one of the organic bases: adenine, cytosine, guanine, or uracil.

What type of bond joins nucleotides in DNA?

Phosphodiester bonds formed in condensation reactions.

What structure does DNA form?

A double helix composed of two polynucleotides.

What is a codon?

A triplet of bases on DNA that codes for a specific amino acid.

What are exons and introns?

Exons are coding regions of DNA, while introns are non-coding sections.

What does it mean that the genetic code is degenerate?

More than one triplet can code for the same amino acid.

What are mutations?

Changes in the base sequence of DNA that can alter the amino acid sequence and potentially affect protein function.

What is the role of RNA polymerase in transcription?

It catalyzes the formation of phosphodiester bonds to create mRNA.

What is the function of mRNA?

It carries the genetic code from DNA to the ribosome for protein synthesis.

What is the structure of tRNA?

A small molecule made of about 80 nucleotides, folded into a cloverleaf shape.

What is the purpose of the anti-codon in tRNA?

It is specific to the amino acid that tRNA carries and matches with the codon on mRNA.

What happens during transcription?

A section of DNA is transcribed into mRNA in the nucleus.

What occurs during the splicing of pre-mRNA?

Introns are removed, leaving only exons to form mature mRNA.

What is the first step of translation?

mRNA attaches to a ribosome.

How do tRNA molecules function during translation?

They collect amino acids from the cytoplasm and carry them to the ribosome.

What is the significance of start and stop codons?

They signal the beginning and end of protein synthesis.

How many chromosomes do humans have?

Humans have 46 chromosomes arranged in homologous pairs.

What determines the sex of an individual in humans?

The 23rd chromosome pair, with females having two X chromosomes and males having one X and one Y chromosome.

What is an allele?

An alternative form of the same gene.

What is the role of histones in eukaryotic cells?

They associate with DNA to form chromosomes.

What type of DNA is found in prokaryotic cells?

Short, circular DNA that is not associated with proteins.

What is the antisense strand in transcription?

The DNA strand used as a template to make mRNA.

What occurs when a stop codon is reached during transcription?

Transcription ceases, and RNA polymerase detaches.

What is the function of peptide bonds?

They join amino acids together to form a polypeptide chain.

What is the genetic code?

The order of bases on DNA that determines the sequence of amino acids in proteins.

What is the role of tRNA in protein synthesis?

tRNA attaches to mRNA by complementary base pairing, bringing amino acids to form a polypeptide chain.

What happens when a stop codon is reached during protein synthesis?

The process of protein synthesis ends, and the polypeptide chain is completed.

How many amino acids can ribosomes join per second?

Ribosomes can join up to 15 amino acids per second.

What is a mutation in genetics?

A mutation is any change in the base sequence or quantity of DNA.

What are the two key types of mutations?

Substitution and deletion.

What is substitution mutation?

It is when one nucleotide in the DNA sequence is replaced by another.

What is deletion mutation?

It is when a nucleotide in the DNA sequence is lost, leading to a frame shift.

What is polyploidy?

It is when an individual has three or more sets of chromosomes instead of two.

What is non-disjunction?

It occurs when chromosomes fail to separate correctly in meiosis, resulting in gametes with an abnormal number of chromosomes.

What is the main role of meiosis?

The production of haploid gametes.

What is independent assortment in meiosis?

It is the random arrangement of homologous chromosomes during meiosis 1.

What is crossing over in meiosis?

It is the exchange of genetic material between homologous chromosomes, leading to genetic variation.

What are the two nuclear divisions in meiosis?

Meiosis 1 and Meiosis 2.

What is genetic diversity?

The total number of different alleles in a population.

What is the niche of a species?

Its role within the environment.

What is natural selection?

The process where fitter individuals survive and pass on advantageous genes to future generations.

What is evolution in the context of genetics?

The process by which the frequency of alleles in a gene pool changes over time due to natural selection.

What is directional selection?

It occurs when environmental conditions change, favoring phenotypes best suited to the new conditions.

What is stabilizing selection?

It preserves phenotypes with successful characteristics and reduces those with greater diversity.

How does antibiotic resistance in bacteria exemplify directional selection?

A mutation allows bacteria to survive antibiotics, leading to increased frequency of the resistance allele in the population.

What is stabilising selection?

A type of natural selection where phenotypes closest to the mean are favored, reducing diversity.

What is an example of stabilising selection?

Newborn baby weights; those around 3kg are more likely to survive.

What is a niche in ecology?

The role of a species within its environment.

What are anatomical adaptations?

Physical adaptations, either external or internal, that enhance survival.

Give an example of an anatomical adaptation.

The long Loop of Henlé in desert mammals for concentrated urine.

What are behavioral adaptations?

Changes in behavior that improve an organism's chance of survival.

What are physiological adaptations?

Processes inside an organism's body that increase its chance of survival.

What is the binomial naming system?

A system for naming species using two Latin or Greek-based names.

What does the generic name in binomial nomenclature represent?

The genus to which the organism belongs.

What does the specific name in binomial nomenclature represent?

The species to which the organism belongs.

What is courtship behavior?

Behavior that enables members of the same species to recognize each other for mating.

What are the purposes of courtship behavior?

To recognize species, synchronize mating, form pair bonds, and enable breeding.

What is classification in biology?

The process of naming and organizing organisms into groups based on characteristics.

What are the five kingdoms of life?

Animals, plants, fungi, prokaryotes, and protoctists.

What is molecular phylogeny?

The analysis of molecular differences to determine evolutionary relatedness.

What are the three domains of life?

Bacteria, Archaea, and Eukaryota.

What is biodiversity?

The variety of living organisms in a given area.

How is species diversity measured?

By counting the number of different species and individuals in a community.

What is ecosystem diversity?

The range of different habitats within a particular area.

What is the index of diversity (D)?

A measure calculated using the total number of organisms and the number of organisms of each species.

How does agriculture impact biodiversity?

It reduces biodiversity by selecting for particular characteristics and limiting species variety.

What are some techniques to maintain biodiversity in agriculture?

Using hedgerows, intercropping, reducing herbicides/pesticides, and preserving wetlands.

What is interspecific variation?

Differences between species.

What is intraspecific variation?

Differences between individuals of the same species.

What is sampling in ecological studies?

The random selection of individuals to measure characteristics of a population.

What is a quadrat?

A tool used to sample organisms in a specific area to eliminate sampling bias.