Comprehensive Genetics, Evolution, and Ecology: Key Concepts and Processes

What are somatic cells?

Body cells that make up tissues and organs, not passed on to offspring.

What are germ cells?

Cells in reproductive organs that develop into gametes (sperm or eggs) and are passed on to children.

How many chromosomes do humans have?

Humans have 46 chromosomes, organized into 23 pairs.

What are sex chromosomes for a person with a uterus?

XX

What are sex chromosomes for a person with testes?

XY

What is a karyotype?

A display of all 46 chromosomes of an individual.

What is the difference between diploid and haploid cells?

Diploid (2n) cells contain both homologous chromosomes (46 total), while haploid (n) cells have half the set (23 total).

What is fertilization?

The fusing of the nucleus of a haploid sperm with the nucleus of a haploid egg.

What is a zygote?

A fertilized egg that is diploid.

What is meiosis?

A type of cell division that reduces the chromosome number by half, resulting in four genetically different haploid cells.

What happens during Meiosis I?

Homologous double-stranded chromosomes separate from each other.

What is tetrad formation?

The pairing of duplicated homologous chromosomes during prophase I.

What is crossing over?

The exchange of genetic material between non-sister chromatids, leading to genetic recombination.

What is independent assortment?

The random arrangement of tetrads along the midline of the cell, creating genetic diversity.

What are the products of Meiosis I?

Two genetically different haploid cells, each with one chromosome from each homologous pair.

What occurs during Meiosis II?

Sister chromatids separate, similar to mitosis, but without preceding DNA duplication.

What is Gregor Mendel known for?

He is known as the 'Father of Genetics' for his work on pea plant variation.

What is the law of segregation?

The principle that organisms inherit two copies of each gene, which segregate during gamete formation.

What is the law of independent assortment?

The principle that allele pairs separate independently during gamete formation.

What is a gene?

A segment of DNA that provides instructions for making a specific protein.

What is the F1 generation in Mendel's experiments?

The first generation of offspring from a cross of purebred plants.

What were Mendel's results for the F2 generation?

75% tall and 25% short offspring from the F1 generation.

What is genetic linkage?

The tendency of genes located close together on a chromosome to be inherited together.

What is cytokinesis?

The division of the cytoplasm during cell division.

What happens during telophase I of meiosis?

Chromosomes arrive at poles, and the nuclear membrane reforms.

What is the significance of crossing over?

It provides a second source of genetic variation by mixing genetic material.

What is the outcome of Meiosis II?

Four genetically different haploid cells are produced.

What is the role of pollen in flowering plants?

Pollen carries sperm to the eggs for fertilization.

How did Mendel prevent self-pollination in his experiments?

He snipped the stamens of flowers.

What does Mendel's second law, the law of independent assortment, state?

Allele pairs separate independently during gamete formation, leading to different traits being inherited separately.

What are genes?

Segments of DNA that provide instructions for making specific proteins, each located at a specific locus on a chromosome.

What are alleles?

Different forms of a gene, such as short plant height vs. tall plant height.

What is a dominant allele?

The allele that expresses its trait whenever it is present, represented by a capital letter (e.g., T).

What is a recessive allele?

The allele that is masked by a dominant allele and only expresses its trait when no dominant allele is present, represented by a lowercase letter (e.g., t).

What is the difference between genotype and phenotype?

Genotype is the combination of alleles (e.g., TT, Tt, tt), while phenotype is the observable trait (e.g., tall or short).

What is a purebred in genetic terms?

An organism that is homozygous for a trait, having two identical alleles (e.g., TT or tt).

What is a hybrid in genetics?

An organism that is heterozygous for a trait, having one dominant and one recessive allele (e.g., Tt).

What is the result of crossing two pure plants (TT x tt)?

All offspring will be hybrids (Tt).

What is the expected outcome when crossing two hybrids (Tt x Tt)?

The expected ratio is 3 tall (TT, Tt, Tt) to 1 short (tt).

What is X-linked recessive inheritance?

A pattern where the allele causing a trait is located on the X chromosome, affecting males more frequently than females.

What is color blindness?

A condition caused by a recessive allele on the X chromosome, leading to difficulty in differentiating between red and green.

What is hemophilia?

A bleeding disorder caused by a recessive allele on the X chromosome, resulting in a lack of clotting factors.

What is incomplete dominance?

A genetic situation where neither allele is completely dominant, resulting in a third phenotype in heterozygotes (e.g., pink flowers from red and white parents).

What is codominance?

A genetic situation where both alleles are fully expressed in the phenotype (e.g., erminette chicken feathers showing both black and white).

What are multiple alleles?

A gene that has more than two alleles, such as the blood type gene with IA, IB, and i alleles.

What are polygenic traits?

Traits that are influenced by two or more genes, such as human skin color and eye color.

What is an epistatic gene?

A gene that can interfere with the expression of other genes, such as albinism affecting pigmentation.

What is a pedigree chart?

A diagram that traces the inheritance of traits in a family, using phenotypes to infer genotypes.

How can you determine if a disorder is dominant or recessive using a pedigree?

A disorder is dominant if every affected person has at least one affected parent; it is recessive if affected individuals can have two normal parents.

What indicates that a trait is sex-linked in a pedigree?

If males are more likely to have the disorder, there is no father-to-son transmission, and the trait may skip generations.

What is the genotype of a color-blind male?

XcY, where Xc represents the recessive allele for color blindness.

What is the genotype of a color-blind female?

XcXc, as she must have two copies of the recessive allele to express the trait.

What is the probability that a son of a carrier mother and normal father will be color blind?

50% chance, as the son can inherit either Xc or XY.

What is the probability of having a hemophiliac male offspring from a heterozygous mother and normal father?

25% chance, as shown in a Punnett square.

What is a dominant trait?

A trait that is expressed in the phenotype even when only one copy of the allele is present.

What is a recessive trait?

A trait that is only expressed in the phenotype when two copies of the allele are present.

How can you determine if a disorder is autosomal?

If both males and females have an equal chance of being afflicted with the trait.

What indicates a sex-linked disorder in a pedigree chart?

Males are more likely to have the disorder, and there is no father-to-son transmission.

What are the two general categories of gene mutations?

Base substitution and base insertion or deletion.

What is a mutation?

Any change in the sequence of nucleotides of DNA or RNA.

What is a mutagen?

Any physical or chemical agent that can change a sequence in DNA or RNA.

What are some examples of mutagens?

X-rays and ultraviolet light.

What is a base substitution mutation?

The replacement of one nitrogen base for another in the DNA sequence.

What is a base insertion mutation?

Adding a nitrogen base to the DNA sequence.

What is a base deletion mutation?

Removing a nitrogen base from the DNA sequence.

What is a frameshift mutation?

A mutation that shifts the reading frame of the genetic code, often caused by base insertion or deletion.

What are the possible effects of mutations?

Mutations can be beneficial, harmful, or neutral.

What is the significance of the sickle cell mutation?

It is an example of a mutation that can have both harmful and beneficial effects.

What environmental factors can affect gene expression?

Temperature, elevation, sunlight, nutrition, activity, and history of illnesses.

What is the role of pedigree charts in genetics?

They help track inheritance patterns and assess the likelihood of genetic disorders in families.

What does it mean if a trait skips a generation in a pedigree?

It may indicate that the trait is recessive or sex-linked.

What is the purpose of creating many copies of a DNA segment?

To facilitate analysis and study of specific genes or mutations.

How quickly can a technique create copies of DNA?

It can create 100 billion copies in just a few hours.

What is the relationship between genotype and phenotype?

Phenotypes are the observable traits influenced by genotypes and environmental factors.

What is the effect of temperature on phenotype?

It can cause changes such as red skin when hot.

How does elevation affect blood cell production?

Higher elevations can lead to increased production of red blood cells.

What is the result of base insertion or deletion?

It usually causes more damage due to a frameshift in the genetic code.

What is the significance of the amino acid sequence in mutations?

It determines the function of proteins, which can be altered by mutations.

What is the first step in interpreting a pedigree chart?

Determine whether the disorder is autosomal or sex-linked.

What are phenotypes?

Phenotypes are how the organism looks, which can be influenced by environmental factors.

How can temperature affect phenotype?

For example, red skin can occur when hot.

What is the Polymerase Chain Reaction (PCR)?

A technique that creates many copies of a DNA segment without using a living cell, allowing for easier study of genes.

What is the purpose of Gel Electrophoresis?

It sorts DNA fragments by length and is used to compare DNA from different sources.

How does Gel Electrophoresis work?

DNA is cut by enzymes, placed in a gel, and shorter fragments move faster towards the positive charge.

What is the function of microarrays?

They examine gene activity in different cells to help researchers learn about genetic diseases.

What is gene therapy?

An experimental technique that uses genes to treat or prevent diseases by inserting genes into patient cells.

What are the four major groups of macromolecules?

Lipids, Carbohydrates, Nucleic Acids, and Proteins.

What is the primary function of proteins?

They serve as building blocks of cellular structures and act as enzyme catalysts.

What are the monomers of proteins?

Amino acids.

What is a polypeptide?

A long chain of amino acids, usually consisting of thousands of amino acids.

What is the process of transcription?

The nitrogen base code in DNA is transcribed into its complementary code in mRNA.

What is RNA splicing?

The process of editing mRNA by removing introns and adding a cap and tail before it leaves the nucleus.

What are the three types of RNA involved in protein synthesis?

mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA).

What is the difference between DNA and RNA in terms of structure?

DNA is double-stranded, while RNA is single-stranded.

What is a codon?

A sequence of three nitrogen bases on mRNA that specifies an amino acid.

What is the start codon for translation?

AUG.

What are stop codons?

Codons that signal the end of translation, such as UAA, UAG, and UGA.

What can cause mutations?

Problems during crossing-over in meiosis, DNA replication, or transcription.

What role do ribosomes play in protein synthesis?

Ribosomes read mRNA and facilitate the linking of amino acids to form proteins.

What happens during translation?

tRNA brings amino acids to the ribosome, where they are linked together to form a polypeptide chain.