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Chapters 8-12
Chromosomes
Long, thread-like structures made of DNA that contain genes. Each species has a specific number of chromosomes.
chromatids
Copy of a chromosome that is formed during cell division, attached to its identical sister chromatid by a centromere.
Mitosis
A type of cell division that results in two genetically identical daughter cells, used for growth and repair of tissues.
Prophase
The first stage of mitosis where chromosomes condense and become visible, and the mitotic spindle begins to form.
Metaphase
The second stage of mitosis in which chromosomes align at the cell's equatorial plane, preparing for separation.
Anaphase
The third stage of mitosis where sister chromatids are pulled apart toward opposite poles of the cell.
Telophase
The fourth stage of mitosis in which the separated chromosomes reach the poles and begin to decondense, and nuclear membranes re-form around each nucleus.
Cytokinesis
The final process of cell division where the cytoplasm divides, resulting in two separate cells.
Human chromosome number and composition
Humans have 46 chromosomes, organized into 23 pairs, including 22 pairs of autosomes and 1 pair of sex chromosomes (XX or XY).
Meiosis
A specialized form of cell division that results in four non-identical gametes, each with half the number of chromosomes of the original cell, crucial for sexual reproduction.
Prophase I
The first stage of meiosis where homologous chromosomes pair and exchange genetic material through crossing-over.
Metaphase I
The stage of meiosis where paired homologous chromosomes align at the cell's equator.
Telophase I
The stage of meiosis where the separated homologous chromosomes arrive at the poles, and the cell prepares to divide.
Prophase II
The stage of meiosis II where chromosomes condense again and spindle fibers form, following a brief interphase.
Metaphase II
The stage of meiosis II where chromosomes align at the equator of the cell, similar to metaphase in mitosis.
Anaphase II
The stage of meiosis II where sister chromatids are separated and move toward opposite poles of the cell.
genetic recombination
Genetic recombination occurs through processes such as crossing over during prophase I of meiosis, where sections of DNA are exchanged between homologous chromosomes.
Nondisjunction
An error in cell division where chromosomes fail to separate properly, leading to gametes with abnormal numbers of chromosomes.
Genes
Units of heredity composed of DNA that carry the information needed to produce proteins and determine traits.
Alleles
Different versions of the same gene that can produce variations in a trait, such as different colors of flowers.
Homozygous
An organism that has two identical alleles for a particular gene, resulting in a uniform trait.
Heterozygous
An organism that has two different alleles for a particular gene, resulting in a mixed trait.
Genotype
The genetic constitution of an organism, encompassing all the alleles present, regardless of whether they are expressed.
Phenotype
The observable characteristics or traits of an organism, which result from the interaction of its genotype with the environment.
Law of Segregation
Mendel's principle stating that during the formation of gametes, the two alleles for a gene separate, so that each gamete carries only one allele for each gene.
Law of Independent Assortment
Mendel's principle that states genes for different traits are inherited independently of each other, provided that the genes are located on different chromosomes.
Law of Dominance
Mendel's principle that states that in a heterozygote, one allele may express its phenotype while the other allele is masked.
Genetic Cross
The intentional mating of two organisms to study the inheritance of specific traits.
Pattern of Inheritance
The observed method by which genetic traits are transmitted from parents to offspring.
Probability Rules
Mathematical rules that predict the likelihood of certain genetic outcomes in offspring based on the alleles of the parents.
Sex-Linked Inheritance
The inheritance patterns of genes located on sex chromosomes, which can lead to different probabilities of traits being expressed in males and females.
Epigenetics
The study of how environmental factors influence gene expression without altering the underlying DNA sequence.
What is DNA made of?
DNA (deoxyribonucleic acid) is made of nucleotides, which consist of a phosphate group, a sugar molecule (deoxyribose), and a nitrogenous base.
What is RNA made of?
RNA (ribonucleic acid) is made of nucleotides, which include a phosphate group, a sugar molecule (ribose), and one of four nitrogenous bases (adenine, uracil, cytosine, or guanine).
Complementary Base Pairing
The rule that specifies how nucleotides pair in DNA and RNA; adenine pairs with thymine (or uracil in RNA), and cytosine pairs with guanine.
Where does Transcription happen?
Transcription occurs in the nucleus of eukaryotic cells, where DNA is converted into mRNA.
What are the stages of Transcription?
The stages of transcription include initiation (starting the synthesis of mRNA), elongation (adding RNA nucleotides to the growing mRNA strand), and termination (ending the synthesis when a stop signal is reached).
Where does Translation occur?
Translation occurs in the cytoplasm at the ribosome, where mRNA is translated into a polypeptide chain.
What are the stages of Translation?
The stages of translation include initiation (assembly of mRNA, ribosome, and initiator tRNA), elongation (adding amino acids to the chain), and termination (release of the finished polypeptide when a stop codon is reached).
RNA Processing
The modification of pre-mRNA into mature mRNA, which includes capping, polyadenylation, and splicing to remove introns.
Restriction Enzyme
Proteins that cut DNA at specific sequences, used in genetic engineering and molecular cloning.
Gel Electrophoresis
A laboratory technique used to separate DNA, RNA, or proteins based on size and charge, allowing for analysis and comparison.
DNA Fragment Separation on Gel
The process of using gel electrophoresis to separate DNA fragments by size; smaller fragments move farther through the gel matrix.
Gene Expression
The process by which information from a gene is used to synthesize functional gene products, like proteins, contributing to phenotypic traits.
Eukaryotic gene regulation
The mechanisms that control the timing, location, and amount of gene expression in eukaryotic cells, allowing for complex development and responses to the environment.
Cancer genes
Genes that are involved in the development of cancer, which may include oncogenes that promote cell growth and tumor suppressor genes that inhibit cell growth.
Inherited Cancer
Cancer that is passed down through families due to inherited genetic mutations that increase the risk of developing certain types of cancer.
