Genetics and Evolution Notes

A comprehensive set of flashcards covering key concepts in genetics, cell biology, evolution, and animal anatomy, designed to aid in exam preparation.

What is the basic structural unit of all living organisms?

Cell

What is the study of how genetic information is passed from one generation to another called?

Genetics

What type of cell undergoes mitosis?

Somatic cell

What carries genetic information and is made of DNA and proteins?

Chromosome

What does the Cell Theory state about cells?

1. Cells are the smallest living organism; 2. All organisms are composed of one or more cells; 3. All cells come from pre-existing cells.

List three functions of cell division.

1. Growth of organism; 2. Repair of damaged tissues and organs; 3. Maintenance to replace dead or dying cells.

How long do most cells take to complete the cell cycle?

12-24 hours.

What are the three stages of the cell cycle?

1. Interphase; 2. Mitosis; 3. Cytokinesis.

What happens during Interphase?

Cell grows, develops into functioning cell, copies DNA to prepare for division.

What characterizes the G1 phase in Interphase?

Major growth phase, preparation for DNA replication.

What occurs during the S (Synthesis) phase of Interphase?

DNA is replicated, existing as chromatin.

Describe the G2 phase in Interphase.

More growth and preparation for mitosis.

What is the result of Mitosis?

Produces 2 daughter cells from one parent cell, all genetically identical.

What happens to chromatin during Prophase?

Chromatin condenses into chromosomes.

How are sister chromatids held together?

By the centromere.

What dissolves during Prophase?

The nucleolus and nuclear membrane.

What occurs during Metaphase?

Spindle fibers move chromosomes to the cell’s equator and attach to centromeres.

What happens during Anaphase?

Centromeres split and sister chromatids separate; spindle fibers shorten.

What occurs in Telophase?

Chromosomes unwind and the nuclear envelope and nucleolus reform.

What is cytokinesis?

The splitting of the cell.

Describe cytokinesis in animal cells.

Indentation at the equator and pinches.

Who identified the structure of DNA?

Rosalind Franklin.

Who developed the DNA model?

James Watson and Francis Crick.

What is the structure of DNA?

Double helix.

What are histones?

Proteins around which DNA coils.

What are nucleosomes?

8 histones with DNA wrapped around.

What is chromatin?

Rope of DNA with proteins.

How is DNA structured in terms of nucleotides?

Formed of nitrogenous base, deoxyribose sugar, phosphate molecule.

What are the nitrogenous bases?

Adenine, Thymine, Guanine, Cytosine.

What base pairs with Adenine?

Thymine.

What base pairs with Guanine?

Cytosine.

What is a genome?

Complete DNA sequence in every cell of an organism.

How many chromosomes do humans have?

46 chromosomes (23 pairs).

What are sex chromosomes?

X and Y (male = XY, female = XX).

What are autosomes?

Remaining 22 chromosomes that are not sex chromosomes.

What are homologous chromosomes?

Pairs of chromosomes with same gene sequence.

What is a gene?

Specific part of a chromosome that dictates a specific trait.

What is an allele?

Different forms of the same gene.

What is karyotyping?

Study of a person’s chromosomes to identify genetic disorders.

What does Meiosis produce?

Genetically unique haploid daughter cells.

What is the difference between asexual and sexual reproduction?

Asexual requires one parent (mitosis), sexual requires two parents (meiosis).

What is a gamete?

Reproductive cells; male gamete is sperm, female gamete is ovum.

What is zygote a result of?

Fusion of male and female gametes during fertilization.

How many copies of each chromosome do gametes have?

One copy (haploid).

How many copies of each chromosome do zygotes and somatic cells have?

Two copies (diploid).

What is genetic reduction?

Produces haploid daughter cells in meiosis.

What does genetic recombination do?

Produces genetically unique daughter cells with different combinations of alleles.

List the stages of Meiosis.

Prophase I, Metaphase I, Anaphase I, Telophase I, and Meiosis II.

What happens during Prophase I?

Homologous chromosomes join tightly together (synapsis).

What characterizes Telophase I?

Each daughter cell becomes haploid.

How does Meiosis II compare to mitosis?

It is similar in process.

What is spermatogenesis?

Sperm production in the testes.

What are spermatogonia?

Parent cells in spermatogenesis.

What do spermatocytes undergo to produce 4 haploid gametes?

Meiosis.

What is oogenesis?

Ovum production in the ovaries.

What are oogonia?

Parent cells in oogenesis.

What happens to the oocyte during meiosis?

Produces 1 haploid gamete (ovum) and 3 polar bodies.

What causes mutations?

Errors in meiosis that cause chromosomal abnormalities.

What is independent assortment?

Random arrangement of homologous chromosomes in metaphase I.

What is crossing over?

Exchange of pieces of chromatid between non-sister chromatids during prophase I.

What is a deletion in chromosome structure?

Part of chromosome is lost.

What is duplication in chromosome structure?

Part of a chromosome is copied more than once.

What is inversion in chromosome structure?

Part of a chromosome is reversed.

What is translocation in chromosome structure?

Part of a chromosome attaches to a different chromosome.

What is nondisjunction?

Failure of homologous chromosomes or sister chromatids to separate properly.

What is monosomy?

One chromosome is lost due to nondisjunction.

What is trisomy?

One chromosome is gained due to nondisjunction.

What is Trisomy 21?

Extra chromosome 21, leads to Down Syndrome.

What is Trisomy 18?

Extra chromosome 18, leads to Edwards Syndrome.

What is Trisomy 13?

Extra chromosome 13, leads to Patau Syndrome.

What does XXY indicate?

Males have an extra X chromosome, leads to Klinefelter Syndrome.

Who is known as the Father of Genetics?

Gregor Mendel.

What did Mendel observe in pea plants?

Patterns of inheritance.

What is selective breeding?

Choosing specific gametes to obtain desired traits.

What is the Law of Segregation?

Alleles separate during gamete formation; each gamete carries one allele per gene.

What is a dominant allele?

An allele that is expressed if present.

What is a recessive allele?

An allele that is expressed only when dominant alleles are not present.

What is phenotype?

The appearance of an organism based on expressed alleles.

What is genotype?

The genetic makeup of an organism.

What is a monohybrid cross?

A genetic cross examining one trait.

In a monohybrid cross, what represents dominant and recessive alleles?

Dominant is capital letter, recessive is lowercase.

What is a test cross?

Unknown parent genotype crossed with homozygous recessive.

What are the results of Mendel's Monohybrid cross in F1 generation?

100% heterozygous genotypes.

What is a dihybrid cross?

A genetic cross examining two traits.

What is codominance?

Both alleles are expressed at the same time.

What is incomplete dominance?

Both alleles are equally dominant, creating a new phenotype (blend).

What are multiple alleles?

More than two possible alleles for a trait.

What is a well-known example of multiple alleles in humans?

Blood types.

What are sex-linked traits?

Traits linked to the X chromosome.

What is a pedigree?

A diagram showing inheritance patterns in a family.

What symbols represent males and females in a pedigree?

Square represents male, circle represents female.

What do shaded symbols indicate in a pedigree?

Affected individuals.

What do half-shaded symbols indicate in a pedigree?

Known heterozygous individuals.

What are adaptations?

Traits that help organisms survive and reproduce in their environment.

What are variations?

Small changes from mutations or sexual reproduction.

What is natural selection?

The process where organisms better adapted to their environment tend to survive.

What are selective pressures?

Environmental factors that make certain traits more advantageous.

What does fitness refer to in evolution?

The contribution of an individual to the gene pool of the next generation.

What is artificial selection?

Humans apply selective pressures to species for desired traits.

What is the Creationism Theory?

The belief that species were created in their current form by a divine being.