Cloning, DNA, and Chromosomes

• Clones are genetically identical copies of an organism.
• Somatic cell nuclear transfer (SCNT) is a reproductive cloning method.
• SCNT involves replacing the nucleus of an unfertilized egg with the DNA from a donor's body cell.
• Differentiation is a process where cells become specialized during development.
• This occurs as different cell lineages begin to use different subsets of their DNA.
• DNA sequence refers to the order of nucleotide bases in a strand of DNA.
• Histones are proteins that associate with the DNA double helix.
• Chromosomes are structures consisting of DNA along with associated proteins.
• The centromere is a constricted region of a duplicated eukaryotic chromosome.
• It is where sister chromatids attach to each other.
• Sister chromatids are two identical DNA molecules attached at the centromere of a duplicated eukaryotic chromosome.
• Diploid cells have two of each type of chromosome characteristic of the species (2n).
• Chromosome number is the total number of chromosomes in a cell of a given species.
• Karyotype is an image of an individual's chromosomes arranged by size, length, shape, and centromere location.
• Sex chromosomes determine anatomical sex.
• Autosomes are chromosome pairs that are the same in males and females.
• DNA replication is the process by which a cell duplicates its DNA before it divides.
• Primers are short, single strands of DNA or RNA that serve as an attachment point for DNA polymerase.
• DNA polymerase is an enzyme that carries out DNA synthesis during DNA replication.
• It uses a DNA template to assemble a complementary strand of DNA.
• Mutations are permanent changes in the DNA sequence of a chromosome.
• Genes are a unit of information encoded in the sequence of nucleotide bases in DNA.
• Gene expression is a multistep process of converting information in a gene into an RNA or protein product.
• Transcription is the process in which a gene is copied into RNA form; it is RNA synthesis.
• Messenger RNA (mRNA) carries protein-building instructions.
• Translation assembles a polypeptide chain according to protein-building information in an mRNA.
• Ribosomal RNA (rRNA) is an RNA component of ribosomes
• Transfer RNA (tRNA) delivers amino acids to a ribosome during translation.
• RNA polymerase is an enzyme that carries out transcription (RNA synthesis).
• A promoter is a special sequence of nucleotide bases in DNA that functions as a binding site for RNA polymerase.
• The promoter is the site where transcription begins.
• An intron is a gene segment that intervenes between exons and is removed from a new RNA during post-transcriptional modification.
• An exon is a gene segment that remains in an RNA after post-transcriptional modification
• Codons are a three-nucleotide unit of information in an mRNA.
• The order of the three bases determines the instruction, most of which specify particular amino acids.
• The genetic code is the complete set of sixty-four codons.
• An anticodon is a set of three nucleotides in a tRNA that base-pairs with an mRNA codon.
• Deletions are a type of mutation in which one or more nucleotides are lost from DNA.
• Insertions are a type of mutation in which one or more nucleotides are inserted into DNA.
• Base-pair substitutions are a type of mutation in which a single base pair changes.
• Transcription factors are regulatory proteins that influence transcription by binding directly to DNA.
• Master regulators are genes whose expression triggers a gene expression cascade that ultimately changes cells in a lineage.
• They change cells from one type to other, more differentiated types.
• Knockouts are a technique of introducing a mutation that disables expression of a gene in an organism.
• Barr body is a condensed, inactivated X chromosome in a body cell of a female mammal.
• This is because the other X chromosome is active).
• Epigenetic refers to potentially heritable modifications to DNA that affect gene expression without changing the DNA sequence.
• Mitosis is a nuclear division mechanism that maintains the chromosome number.
• Mitosis is the basis of body growth and tissue repair in multicell eukaryotes also asexual reproduction in some eukaryotes.
• Mitosis occurs in four stages: prophase, metaphase, anaphase, and telophase.
• Homologous chromosomes are chromosomes in a cell nucleus that have same length, shape, and set of genes.
• Asexual reproduction is a reproductive mode by which offspring arise from a single parent only.
• Interphase is the interval between divisions in a eukaryotic cell cycle.
• During interphase, the cell grows, roughly doubles the number of its cytoplasmic components, and replicates its DNA.
• The cell cycle is the collective series of intervals and events of a eukaryotic cell's life, from the time it forms until it divides.
• Prophase is the stage of mitosis during which chromosomes condense and become attached to a newly forming spindle.
• The spindle is a temporary structure that moves chromosomes during nuclear division.
• It consists of microtubules that elongate from two spindle poles.
• Metaphase is the stage of mitosis at which all chromosomes are aligned midway between spindle poles.
• Anaphase is the stage of mitosis during which sister chromatids separate and move toward opposite spindle poles.
• Telophase is the stage of mitosis during which chromosomes arrive at the spindle poles and become enclosed by a new nuclear envelope.
• Cleavage furrow refers to the indentation where cytoplasmic division occurs in a dividing animal cell.
• A tumor is a mass of abnormally dividing cells in a tissue.
• Metastasis is the process by which cells of a malignant tumor spread from one part of the body to another.
• Cancer is a group of diseases characterized by malignant cells
• These are abnormally dividing cells that can migrate to other body tissues).
• Sexual reproduction is a reproductive mode by which offspring arise from two parents and inherit genes from both.
• Meiosis as a nuclear division process that halves the chromosome number for forthcoming gametes.
• Meiosis is the basis of sexual reproduction.
• Crossing over is the process in which homologous chromosomes exchange corresponding segments during prophase I of meiosis.
• Haploid (n) cells have one of each type of chromosome characteristic of the species.
• Gametes are mature, haploid reproductive cells, such as an egg or a sperm.
• A zygote is a diploid cell that forms when two gametes fuse; it is the first cell of a new individual.
• Genotype is the particular set of alleles carried by an individual.
• Phenotype is an individual's observable traits.
• Homozygous indicates same allele of a gene.
• Heterozygous indicates different alleles of a gene
• Dominant is an allele that masks the effect of a recessive allele.
• Recessive is an allele with an effect that is masked by a dominant allele.
• Monohybrid Cross involves a cross between two individuals identically heterozygous for alleles of one gene ex. (Aa x Aa) (2x2).
• Dihybrid cross involves the cross between two individuals identically heterozygous for alleles of two genes ex. (AaBb x AaBb) (4x4).
• Punnett square predicts the genotypic and phenotypic outcomes of a cross.
• Incomplete dominance happens when one allele is not fully dominant over another.
• The heterozygous phenotype is intermediate between the two homozygous phenotypes.
• Codominance happens when two alleles are both fully expressed in heterozygous individuals.
• Polygenic inheritance is inheritance in which multiple genes affect one trait.
• Pleiotropy is an inheritance pattern in which a single gene affects multiple traits.
• Continuous variation shows a range of small differences in forms of a trait.
• Bell Curve is a Bell shaped curve
• Short Tandem Repeat is a region in which a sequence of a few nucleotides is repeated multiple times in a row.
• Pedigrees show whether a trait is associated with a dominant or recessive allele.
• Pedigrees also show whether a trait is on an autosome or sex chromosome.
• Nondisjunction occurs when there is a failure of chromosomes to separate properly during mitosis or meiosis.
• Polyploidy is when there are three or more of each type of chromosome characteristic of the species
• Aneuploidy is when there are too many or too few copies of a particular chromosome
• Whereas polyploidy is having three or more of each type of chromosome characteristic of the species.
• Nondisjunction is a failure of chromosomes to separate normally during meiosis or mitosis.
• Klinefelter Syndrome is a Male Sex Chromosome Abnormality (XXY Syndrome)
• Turner Syndrome is a Female Sex Chromosome Abnormality (XXX Syndrome)
• Down Syndrome - Nondisjunction leading to trisomy 21 increases with age of the mother.
• X-linked recessive disorders are more common in males than in females.
• Alleles on the X chromosome are inherited and expressed differently in males and females.
• Males do not transmit X - linked alleles to their sons, while females pass X-linked alleles to male and female offspring. (Sex linked).
• An autosomal dominant allele is expressed in both homozygotes and heterozygotes.
• An autosomal recessive allele is expressed only in homozygotes.
• Pedigrees show whether a trait is associated with a dominant or recessive allele and whether a trait is on an autosome (22) or sex chromosome (23).
• Codominance refers to two alleles that are both fully expressed in heterozygous individuals.
• Incomplete dominance is when one allele is not fully dominant over another, so the heterozygous phenotype is intermediate between the two homozygous phenotypes.
• Polygenic inheritance refers to the inheritance of a trait governed by more than one gene.
• Pleiotropic inheritance is when a single gene influence multiple traits.
• Mono= One Monohybrid Cross where individuals w/ different alleles of a gene are crossed and show probability of genotype ratio 3:1 for one trait crossed.
• Dihybrid Cross involves two genes of different crossed alleles and displays how the probability of the genotype ratio 9:3:3:1 turns out.
• Metastasis describes the development of secondary malignant growths at a distance from a primary site of cancer.
• Malignant Cancer cells can spread throughout the body via the blood or lymphatic system, which is known as metastasis.
• This occurs because of uncontrolled growth.
• A tumor is any swelling of a part of the body, generally without inflammation, caused by an abnormal growth of tissue, whether benign or malignant.
• Oncogenes transform a cell into a tumor cell in certain circumstances
• Tumor suppressor genes acting to inhibit cell proliferation and tumor development.
• Gametes are specialized reproductive cells that carry half the genetic material of an organism.
• Gametes are crucial for sexual reproduction and produced during Meiosis during Metaphase I.
• mRNA (messenger RNA) provides template for protein synthesis during translation
• rRNA (ribosomal RNA) plays a structural and catalytic role during translation
• tRNA (transfer RNA) delivers amino acids to ribosomes during translation.
• Semiconservative Model: Results in two DNA molecules with one original strand and one new strand.
• Nondisjunction is the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division.
• In cases like this, expect an abnormal distribution of chromosomes in the daughter nuclei at the end of Meiosis I.
• Chromosome number/arrangement for the average human female: 46 chromosomes, 1-22 autosomes pairs, 1 pair of sex chromosomes XX (at 23)
• Chromosome number/arrangement for the average human male: 46 chromosomes, 1-22 autosomes pairs, 1 pair of sex chromosomes XY (at 23).
• Autosomes are chromosomes that carry most of an organism's genes.
• Sex chromosomes determine sex.
• DNA’s bases: A-T, C-G
• RNA’s bases: A-U, C-G
• Hydrogen bonds hold the DNA base pairs together.
• Hershey & Chase showed that only DNA of a virus needs to enter a bacterium to infect it.
• Rosalind Franklin discovered the structure of DNA by photo 51 X-ray crystallography
• Watson and Crick built the first double helix structure of DNA.
• Chargaff's Rules shows bases of the two DNA strands in a double helix pain in a consistent way: A-T and C-G

Learn about cloning, somatic cell nuclear transfer, and cell differentiation. Explore DNA sequences, histones, chromosomes, centromeres, and chromatids. Understand diploid cells and chromosome number.