Unit Review: Biology – Genetics Processes (Video)

A set of practice flashcards covering key concepts from the Genetics Processes video notes.

What does DNA stand for?

Deoxyribonucleic acid.

What are the three main structural components of DNA?

Deoxyribose sugar, phosphate backbone, and nitrogenous bases (A, T, C, G).

What are the base-pairing rules in DNA?

Adenine pairs with thymine (A-T) and cytosine pairs with guanine (C-G).

Describe the DNA double helix and the orientation of its strands.

Two anti-parallel strands form a double helix; 5' to 3' orientation is opposite in each strand.

Differentiate chromosome, chromatin, gene, and locus.

Chromosome is condensed DNA during cell division; chromatin is relaxed DNA during interphase; a gene is a unit of heredity; a locus is the location of a gene on a chromosome.

Define diploid, haploid, and polyploid.

Diploid (2n) has two sets of chromosomes; haploid (n) has one set; polyploid has more than two sets.

What is asexual reproduction?

Reproduction without fertilization, producing genetically identical offspring via mitosis.

List the stages of the cell cycle.

Interphase (G1, S, G2) and the M phase (mitosis and cytokinesis).

Name the stages of mitosis in order and a key event for each.

Prophase (chromosomes condense); Prometaphase (nuclear envelope breaks); Metaphase (chromosomes align at the metaphase plate); Anaphase (sister chromatids separate); Telophase (nuclear envelopes reform); Cytokinesis (cytoplasm divides).

Describe sexual reproduction.

Reproduction involving two parents and fertilization, producing genetically diverse offspring.

What are meiosis I and meiosis II, and what are their key differences?

Meiosis I separates homologous chromosomes and includes crossing over; Meiosis II separates sister chromatids, resembling mitosis; meiosis reduces chromosome number.

Define homologous chromosomes, sister chromatids, and chromatid pairs.

Homologous chromosomes are chromosome pairs with the same genes; sister chromatids are identical copies held at the centromere after replication; chromatid pairs refer to the two chromatids of a replicated chromosome.

Explain crossing over and its significance.

Exchange of genetic material between homologous chromosomes during prophase I, increasing genetic variation.

Explain independent assortment.

Random orientation of homologous chromosome pairs during metaphase I, contributing to variation in gametes.

Compare advantages and disadvantages of asexual vs sexual reproduction.

Asexual: fast, no mate, no genetic variation; Disadvantage: no variation. Sexual: creates genetic variation, supports adaptation; Disadvantage: requires two parents and more energy.

What are the similarities and differences between mitosis and meiosis?

Mitosis: one division, two identical diploid daughter cells, maintains chromosome number. Meiosis: two divisions, four haploid cells, introduces genetic variation and reduces chromosome number.

Define gametogenesis, oogenesis, and spermatogenesis.

Gametogenesis is the formation of gametes; oogenesis is egg production in females; spermatogenesis is sperm production in males.

Describe nondisjunction and its consequences.

Failure of homologous chromosomes or sister chromatids to separate during meiosis; results in aneuploidy (monosomy or trisomy).

What is a karyotype and how is it used?

A chart of an individual’s chromosomes used to identify chromosomal disorders and determine sex.

Define monosomy and trisomy.

Monosomy: missing one chromosome (2n-1); trisomy: extra chromosome (2n+1).

What is Down syndrome?

Trisomy 21, the presence of an extra chromosome 21.

What is Turner syndrome?

Monosomy X (45,X), a female with a single X chromosome.

P generation in Mendelian genetics.

Parental generation used to establish the cross; provides the genotypes/phenotypes for predicting offspring.

Differentiate homozygous and heterozygous; dominant and recessive.

Homozygous: two identical alleles; heterozygous: two different alleles; dominant: allele that masks the other; recessive: allele that is masked.

Define monohybrid cross.

A cross examining the inheritance of a single trait; involves P, F1, F2; genotype and phenotype ratios.

Define dihybrid cross.

A cross examining two traits simultaneously; expects a 9:3:3:1 phenotypic ratio in the F2 under complete dominance.

Differentiate incomplete dominance and codominance.

Incomplete dominance: heterozygote shows an intermediate phenotype; Codominance: both alleles are expressed equally (e.g., AB blood type).

Explain sex-linked inheritance and the ABO blood type system.

Sex-linked inheritance follows the X chromosome; ABO system shows codominance among IA and IB with i; genotypes determine phenotype.

What is a Punnett square used for?

A grid to predict offspring genotypes and phenotypes from parental genotypes; can be applied to sex-linked and blood type problems.

Explain the concept of universal donor and universal recipient in blood types.

Universal donor: O negative; universal recipient: AB positive.

What is an allele and a gene?

An allele is a variant form of a gene; a gene is a unit of heredity located at a locus on a chromosome.

What is a locus?

The specific physical location of a gene on a chromosome.

What is the difference between autosomes and sex chromosomes?

Autosomes are non-sex chromosomes; sex chromosomes determine sex (X and Y in humans).

What is a centromere?

The region of a chromosome where sister chromatids are held together and where spindle fibers attach during mitosis.

What is crossing over and where does it occur?

Crossing over is the exchange of genetic material between homologous chromosomes during prophase I of meiosis.