Module Four Flashcards
What is a genome?
The complete set of genetic material in an organism, including both DNA (genes and non-coding regions) and, in some cases, RNA.
What are chromosomes, and what are they made of?
Chromosomes are structures within cells that organize and package DNA. They are made of chromatin, a combination of DNA and proteins like histones.
How many chromosomes do humans have?
Humans have 46 chromosomes, organized into 23 pairs.
What are the phases of the cell cycle?
Interphase:
G1: The cell grows.
S: DNA is synthesized (replicated).
G2: The cell prepares for division.
M Phase: Includes mitosis (division of the nucleus) and cytokinesis (division of the cytoplasm).
How is the cell cycle regulated?
The cell cycle is regulated by checkpoints (e.g., G1/S, G2/M) to ensure each stage is completed correctly.
Cyclins and cyclin-dependent kinases (CDKs) control the progression through the cycle. Cyclins bind to CDKs to activate them, enabling the cell to move to the next phase.
What are the stages of mitosis, and what happens in each?
Prophase: Chromosomes condense, and the mitotic spindle begins to form. The nuclear envelope breaks down.
Metaphase: Chromosomes align at the metaphase plate in the center of the cell.
Anaphase: Sister chromatids are pulled apart by the spindle fibers toward opposite poles of the cell.
Telophase: The nuclear envelope reforms around the separated chromosomes, which decondense.
What is cytokinesis, and how does it differ in plant and animal cells?
Cytokinesis is the division of the cytoplasm.
In animal cells, a cleavage furrow forms, pinching the cell in two.
In plant cells, a cell plate forms between the dividing cells, eventually becoming the new cell wall.
Who was Henrietta Lacks, and why are her cells significant?
Henrietta Lacks was a woman whose cancer cells, known as HeLa cells, were the first human cells successfully cultured in a lab. These “immortal” cells have been used in countless scientific breakthroughs, raising ethical concerns about consent
What are the two types of reproduction, and how do they differ?
Asexual Reproduction: Involves a single parent producing genetically identical offspring (e.g., binary fission in bacteria).
Sexual Reproduction: Involves two parents, resulting in genetically diverse offspring through the combination of gametes (sperm and egg).
What is the sexual life cycle?
The sequence of events in an organism’s life that includes the production of gametes (sperm and egg), fertilization, and the development of offspring.
What are homologous chromosomes?
Chromosome pairs, one from each parent, that have the same genes but may contain different alleles.
What are the three types of sexual life cycles, and how do they differ?
Diploid-dominant: Most of the life is spent in the diploid state (e.g., humans).
Haploid-dominant: Most of the life is spent in the haploid state (e.g., fungi).
Alternation of generations: Alternates between haploid (gametophyte) and diploid (sporophyte) stages (e.g., plants).
What is meiosis, and why is it important?
Meiosis is a type of cell division that reduces chromosome numbers by half, producing four haploid gametes. It is crucial for sexual reproduction and contributes to genetic variability.
What are the stages of meiosis, and what happens in each?
Meiosis I:
Prophase I: Homologous chromosomes pair up and exchange DNA (crossing over).
Metaphase I: Homologous pairs align at the cell’s center.
Anaphase I: Homologous chromosomes separate.
Telophase I and Cytokinesis: Two haploid cells form.
Meiosis II:
Prophase II: Spindle fibers form.
Metaphase II: Chromosomes align at the center.
Anaphase II: Sister chromatids separate.
Telophase II and Cytokinesis: Four haploid gametes are produced.
How does meiosis generate genetic variability?
Crossing Over: During Prophase I, homologous chromosomes exchange genetic material.
Independent Assortment: Chromosomes are distributed randomly to gametes during Metaphase I.
Random Fertilization: Any sperm can fertilize any egg, adding to diversity.
