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What are genes?
Segments of DNA that code for traits and are passed from parents to offspring.
What are gametes?
Reproductive cells (sperm and egg) that carry genes to the next generation.
What is a locus?
The specific location of a gene on a chromosome.
What is a karyotype?
A picture of an organism’s complete set of chromosomes arranged in pairs.
What is asexual reproduction?
A single parent passes all its genes to offspring, creating a genetically identical clone.
What is sexual reproduction?
Two parents contribute genes, increasing genetic variation in offspring.
What are somatic cells?
Body cells that are not gametes (e.g., liver cells, neurons).
How many chromosomes do human somatic cells have?
46 chromosomes (23 pairs).
What are homologous chromosomes?
Pairs of chromosomes that have the same genes but may have different versions (one from each parent).
What are autosomes?
Non-sex chromosomes (22 pairs in humans).
What are sex chromosomes?
XX or XY
What does haploid (n) mean?
A cell with half the number of chromosomes (e.g., gametes have 23 chromosomes).
What does diploid (2n) mean?
A cell with two sets of chromosomes (e.g., zygote has 46 chromosomes).
What is meiosis?
A type of cell division that reduces the chromosome number by half to form gametes.
What is fertilization?
The fusion of a haploid sperm and egg to form a diploid zygote.
How does meiosis create genetic variation?
Through independent assortment and crossing over.
How is meiosis different from mitosis?
Meiosis: 2 divisions, 4 genetically unique haploid cells.
Mitosis: 1 division, 2 identical diploid cells.
What are the two stages of meiosis?
Meiosis I – Homologous chromosomes separate.
Meiosis II – Sister chromatids separate.
What happens in Prophase I?
Chromosomes condense.
Homologous chromosomes pair up (synapsis) to form tetrads.
Crossing over occurs, exchanging DNA for genetic diversity.
What happens in Metaphase I?
Homologous chromosome pairs align at the metaphase plate.
Independent assortment occurs, increasing variation.
What happens in Anaphase I?
Homologous chromosomes are pulled apart.
Sister chromatids remain together.
What happens in Telophase I & Cytokinesis?
Two haploid cells form, each with half the original chromosome number.
What happens in Prophase II?
A new spindle forms, and sister chromatids prepare to separate.
What happens in Metaphase II?
Chromosomes line up at the metaphase plate.
What happens in Anaphase II?
Sister chromatids separate and move to opposite poles.
What happens in Telophase II & Cytokinesis?
Four haploid daughter cells form, each genetically unique
What is crossing over?
The exchange of DNA between homologous chromosomes during Prophase I.
What is independent assortment?
The random sorting of maternal and paternal chromosomes during Metaphase I.
What is random fertilization?
The random pairing of unique sperm and egg, creating trillions of possible genetic combinations.
