Chapter 7: Cloning & Chromosome Key Terms

Biology Overview

• Biology is the science of life, exploring the structure, function, growth, origin, evolution, and distribution of living organisms.

Core Principles of Biology

• All living organisms are composed of one or more cells (cell theory).
• Hereditary information is encoded in genes and passed down through generations (gene theory).
• Life evolves over time through processes like natural selection (evolution).
• Living organisms maintain a stable internal environment (homeostasis).

Levels of Biological Organization

• Atoms combine to form molecules, such as DNA and proteins.
• Cells are the basic unit of life, enclosed by a membrane and containing organelles.
• Tissues are groups of similar cells performing a specific function.
• Organs are composed of different tissues working together.
• Organ systems are groups of organs that perform major bodily functions.
• Organisms are individual living entities.
• Populations are groups of individuals of the same species in the same area.
• Communities are populations of different species interacting.
• Ecosystems are communities interacting with their physical environment.
• The biosphere is the entire portion of Earth inhabited by life.

Cell Structure and Function

• Prokaryotic cells lack a nucleus and other membrane-bound organelles; examples include Bacteria and Archaea.
• Eukaryotic cells possess a nucleus and other membrane-bound organelles; examples include Eukarya (protists, fungi, plants, and animals).
• The plasma membrane is the outer boundary of the cell, which regulates the passage of substances.
• The nucleus contains the cell's DNA and controls cellular activities.
• Ribosomes synthesize proteins.
• The endoplasmic reticulum (ER) is involved in protein and lipid synthesis.
• The Golgi apparatus modifies, sorts, and packages proteins.
• Mitochondria generate ATP through cellular respiration.
• Chloroplasts (in plant cells) conduct photosynthesis.

Genetics and Heredity

• DNA, or deoxyribonucleic acid, carries hereditary information.
• Genes are segments of DNA that code for specific traits and are a unit of information encoded in the sequence of nucleotide bases in DNA.
• Chromosomes are structures made of DNA and proteins that carry genes.
• DNA replication is the process of copying DNA.
• Transcription is the process of synthesizing RNA from DNA.
• Translation is the process of synthesizing proteins from RNA.
• Mutations are changes in the DNA sequence.
• Mendelian genetics are principles of inheritance based on Gregor Mendel's work.
• The genotype is the genetic makeup of an organism.
• The phenotype is the observable characteristics of an organism.

Evolution and Natural Selection

• Evolution is the change in the genetic makeup of a population over time.
• Natural selection is the process by which organisms with advantageous traits are more likely to survive and reproduce.
• Adaptation is a trait that enhances an organism's survival and reproduction.
• A species is a group of organisms that can interbreed and produce fertile offspring.
• Speciation is the process by which new species arise.
• Evidence for evolution includes the fossil record, comparative anatomy, embryology, molecular biology, and biogeography.

Ecology

• Ecology studies the interactions between organisms and their environment.
• Population ecology focuses on the dynamics of populations and the factors that affect their size and distribution.
• Community ecology examines the interactions between different species in a community.
• Ecosystem ecology studies the flow of energy and nutrients through ecosystems.
• Biomes are major types of ecosystems characterized by specific climate conditions and dominant plant communities.
• Food chains and food webs are models showing energy flow through an ecosystem.
• Trophic levels are the position an organism occupies in a food chain.
• Biogeochemical cyclesdescribe the movement of elements and compounds through biotic and abiotic components.

Diversity of Life

• Bacteria are single-celled prokaryotes.
• Archaea are single-celled prokaryotes, often found in extreme environments.
• Eukarya are organisms with eukaryotic cells.
• Protists are a diverse group of eukaryotic microorganisms.
• Fungi are heterotrophic eukaryotes that obtain nutrients by absorption.
• Plants are autotrophic eukaryotes that produce food through photosynthesis.
• Animals are heterotrophic eukaryotes that obtain nutrients by ingestion.

Plant Biology

• Photosynthesis is the process by which plants convert light energy into chemical energy.
• Plant structures include roots, stems, leaves, and flowers.
• Plant reproduction can be sexual or asexual.
• Plant adaptations are adaptations to different environments.

Animal Biology

• Animal classification is based on characteristics such as body plan, symmetry, and development.
• Animal tissues include epithelial, connective, muscle, and nervous tissues.
• Animal organ systems include digestive, respiratory, circulatory, excretory, nervous, endocrine, immune, reproductive, skeletal, and muscular systems.
• Animal behavior includes responses to stimuli and interactions with other organisms.

Physiology

• Physiology is the function and processes of living organisms.
• Homeostasis is the process by which organisms maintain a stable internal environment, despite changes in external conditions.
• Respiration is the process by which organisms exchange gases with their environment.
• Excretion is the process by which organisms eliminate waste products.

Microbiology

• Microbiology studies microorganisms, including bacteria, viruses, fungi, and protozoa.
• Roles of microorganisms include nutrient cycling, decomposition, and disease.
• Applications of microbiology include medicine, agriculture, and industry.

Biotechnology

• Biotechnology is the use of biological systems and organisms to develop new technologies and products.
• Genetic engineering is the modification of an organism's genes.
• Cloning is producing genetically identical copies of an organism.
• Applications of biotechnology include medicine, agriculture, and industry.

Important Biological Processes

• Cellular respiration is the process by which cells break down glucose to produce ATP.
• Photosynthesis is the process by which plants convert light energy into chemical energy.
• Osmosis is the movement of water across a semipermeable membrane.
• Active transport is the movement of molecules against their concentration gradient, requiring energy.

Scientific Method

• Observation involves gathering information about a phenomenon.
• A hypothesis is a testable explanation for an observation.
• An experiment is a controlled test of a hypothesis.
• Data analysis involves interpreting the results of an experiment.
• A conclusion is a statement about whether the results support the hypothesis.
• Communication involves sharing the results with the scientific community.

Chapter 7 Key Terms

• Clones are genetically identical copies of an organism.
• Somatic Cell Nuclear Transfer (SCNT) is a reproductive cloning method where the nucleus of an unfertilized egg is replaced with the DNA of a donor's body cell.
• Differentiation is the process in which cells become specialized during development, occurring as different cell lineages use different subsets of their DNA.
• A DNA sequence is the order of nucleotide bases in a strand of DNA.
• Histones are a type of protein associated with the DNA double helix.
• Chromosomes are structures consisting of DNA together with associated proteins. A centromere is the constricted region of a duplicated eukaryotic chromosome, where sister chromatids attach to each other.
• Sister Chromatids are two identical DNA molecules of a duplicated eukaryotic chromosome, attached to one another at the centromere.
• Diploid refers to having 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 complement of chromosomes arranged by size, length, shape, and centromere location.
• Sex chromosomes are chromosomes involved in determining anatomical sex.
• Autosomes are chromosomes of a pair 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.

History and Contributors to DNA Structure and Function

• Erwin Chargaff's rules state that bases of two DNA strands in a double helix pair in a consistent way: A-T and C-G.
• DNA nucleotide composition is calculated as A=T, G=C, with (A=T) + (G=C) = 100%.
• Watson and Crick built the first double helix structure of DNA.
• Rosalind Franklin discovered the structure of DNA by photo 51 X-ray crystallography
• Hershey & Chase showed that only the DNA of a virus needs to enter a bacterium to infect it.

Leveled Organization of Genes

• Sister chromatids are two identical halves of a duplicated eukaryotic chromosome.
• Sister chromatids are organized within the chromosome as one of two attached members of a duplicated eukaryotic chromosome.
• A centromere is a constricted region in a eukaryotic chromosome where sister chromatids are attached.
• Histones help to condense DNA into chromosomes.
• The components of a nucleotide are sugar (deoxyribose), phosphate groups (3), and nitrogenous bases (adenine, thymine, cytosine, guanine).
• The nitrogenous base differentiates each nucleotide.
• Base pairing is the specific way that nitrogenous bases in DNA and RNA bond with each other.
  • DNA replication: A-T, C-G.
  • Transcription and Translation: A-U, C-G.
• Nucleotide bases include adenine, thymine, cytosine, and guanine.
• DNA contains A-T, C-G, while RNA contains A-U, C-G.
• Hydrogen bonds hold the DNA base pairs together.
• The sequence of bases contributes to the diversity among species; DNA sequences are organized into genes.

Chromosomes

• Autosomes carry most of an organism's genes, while sex chromosomes determine sex.
• The average human female has 46 chromosomes: 1-22 autosome pairs and 1 pair of sex chromosomes (XX).
• The average human male has 46 chromosomes: 1-22 autosome pairs and 1 pair of sex chromosomes (XY).
• A diploid cell contains two complete sets of chromosomes, one from each parent (Think 2n).
• A haploid cell has a single set of unpaired chromosomes (Think n).
• A karyotype is an individual's complete set of chromosomes.
• Karyotypes provide information such as sex and sex aneuploidies.
  • Klinefelter Syndrome: 47, XXY (males with an extra X chromosome).
  • Triple X Syndrome: 47, XXX (females with an extra X).
  • XYY Syndrome: 47, XYY (males with an extra Y chromosome).
• Nondisjunction is the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, resulting in an abnormal distribution of chromosomes causing aneuploidy.

DNA Replication

• DNA polymerase, a replication enzyme, assembles a new strand of DNA based on the sequence of a DNA template.
• DNA ligase is an enzyme that seals breaks in double-stranded DNA.
• A primer is a short, single-stranded nucleic acid used by all living organisms in initiating DNA synthesis, allowing DNA polymerase to bind.
• The semiconservative model results in two DNA molecules; each consists of one original strand and one newly synthesized strand.
• DNA replication involves three major steps: initiation, elongation, and termination.
  • Helicase breaks the hydrogen bonds separating the DNA strands.
  • SSB proteins prevent the DNA from recoiling.
  • Primase primes the template strand.
  • DNA polymerase assembles the new DNA segment.
• DNA replication results in two identical DNA molecules, each consisting of one original (parent) strand and one newly synthesized (daughter) strand.
• A mutation is a permanent change in the DNA.
• Ultraviolet light/sunlight causes nucleotide dimers.
• Covalent bonds form between adjacent thymine or cytosine bases, making a kink in the DNA double helix.
• Uncorrected errors in DNA replication lead to mutations, which are permanent changes in the DNA sequence of a chromosome.
• DNA is comprised of 4 nitrogen bases.
• Hydrogen bonds exist between the two strands of DNA.
• DNA polymerase replicates and proofreads.
• DNA primer starts the DNA replication.
• DNA ligase closes everything up.

Chapter 8 Key Terms

• Genes are a unit of information encoded in the sequence of nucleotide bases in DNA.
• Gene expression is the multi-step process of converting information in a gene into an RNA or protein product.
• Transcription is RNA synthesis, the process in which a gene is copied into RNA form.
• Messenger RNA (mRNA) carries protein-building instructions.
• Translation is the process by which a polypeptide chain is assembled according to the 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 the enzyme that carries out transcription (RNA synthesis).
• A promoter in DNA is a special sequence of nucleotide bases that functions as a binding site for RNA polymerase, 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 and most specify particular amino acids.
• The genetic code is a 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 from one type to other, more differentiated types.
• Knockouts are techniques of introducing mutations that disable the expression of a gene in an organism.
• A Barr body is a condensed, inactivated X chromosome in a body cell of a female mammal, where the other X chromosome is active.
• Epigenetic refers to potentially heritable modifications to DNA that affect gene expression without changing the DNA sequence.

Gene Expression (Transcription and Translation)

• A gene is information encoded in the sequence of nucleotides in DNA.
• Gene expression is the process by which the information in a gene becomes converted to an RNA or protein product.
  • Gene expression involves transcription (DNA to mRNA) and translation (mRNA to protein).

Comparison of DNA and RNA

• DNA's main form is a double helix; RNA is mostly single-stranded.
• DNA monomers are deoxyribonucleotides; RNA monomers are ribonucleotides.
• DNA contains deoxyribose sugar; RNA contains ribose sugar.
• DNA contains the bases adenine, guanine, cytosine, and thymine; RNA contains adenine, guanine, cytosine, and uracil.
• DNA base pairing is A-T, G-C; RNA base pairing is A-U, G-C.
• DNA stores genetic information in the nucleus; RNA functions in protein synthesis and other roles, depending on type, in the nucleus and cytoplasm.
• DNA transcription is the process of enzymes using the gene's DNA sequence as a template to assemble a strand of messenger RNA (mRNA).
• In transcription, RNA polymerase binds to a promoter sequence near the beginning of a gene.
• RNA polymerase links RNA nucleotides in the order determined by the base sequence of the gene.
• The new mRNA is a copy of the gene from which it was transcribed.
• Eukaryotic mRNA undergoes alternative splicing where exons refer to the coding portions of DNA or RNA ,and introns refer to non-coding sequences found in DNA or RNA.
• A complementary copy of the DNA template strand, with uracil (U) replacing thymine (T), would look like RNA after transcription.
  • The RNA sequence is identical to the DNA coding strand (except for the U/T swap) and is synthesized in the 5' to 3' direction.
• RNA codons are 3 nitrogen bases together forming an RNA and start is AUG, and stop codons are UAA, UAG and UGA.
• Translation is the second part of protein synthesis, which occurs in the cytoplasm of all cells.
• mRNA is transcribed in the nucleus.
• In the cytoplasm, a small ribosomal subunit binds to mRNA.
  • Initiator tRNA base pairs with the first mRNA codon.
  • The large ribosomal subunit joins the small subunit.
  • The ribosome assembles a polypeptide chain.
  • Translation ends when the ribosome encounters a stop codon.
• Through translation, mRNA is decoded in a sequence of amino acids, resulting in a polypeptide chain that folds into a protein.
• mRNA (messenger RNA) provides the 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.
• Base-pair substitution is a type of mutation in which a single base pair changes.
  • A base pair ex. Sickle cell anemia.
• Substituion Frameshift are mutations that shifts the reading frame of the mRNA codons.
  • Deletion is the deletion of one or more base pairs ex. Beta thalassemia
• Researchers study the function of a homeotic gene by altering its expression by introducing a mutation or deleting it entirely (gene knockout)
• Heritable changes in a gene expression that are not due to changes in the underlying DNA sequence are epigenetic.
• All parental methyl groups are not removed, so some methylations can be passed to future offspring.
• Transcription happens in the nucleolus.
• tRNA translation matches the right anticodon.
• Hydrogen bonds bond out base pairs together.

Chapter 9 Key terms

• Mitosis is a nuclear division mechanism that maintains the chromosome number and the basis of body growth and tissue repair in multicellular eukaryotes; also, asexual reproduction in some eukaryotes.
  • Mitosis occurs in four stages: prophase, metaphase, anaphase, and telophase.
• Homologous chromosomes are chromosomes that have the same length, shape, and set of genes in a cell nucleus.
• Asexual reproduction is a reproductive mode by which offspring arise from a single parent only.
• Interphase in a eukaryotic cell cycle is the interval between divisions during which 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 and 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.
• A cleavage furrow is the indentation in a dividing animal cell where cytoplasmic division will occur.
• A tumor is a mass of abnormally dividing cells in a tissue.
• Metastasis is the process in 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 (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 halves the chromosome number for forthcoming gametes.
• The division process 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) refers to having one of each type of chromosome characteristic of the species.
• Gametes are mature, haploid reproductive cells, e.g., an egg or a sperm.
• A zygote is a diploid cell that forms when two gametes fuse: the first cell of a new individual.
• Mitosis produces 2 identical cells.
• Interphase is the start of Mitosis.

Cell Cycle

• What are some of the benefits of using cell lines to study human diseases?
• Understanding why cancer cells are immortal and understanding the structures and mechanisms that cells use to divide.
• Microtubules is a cytoskeletal element of eukaryotes that forms a dynamic scaffolding for many cellular processes involving movement.
• Hollow filament of tubulin subunits.
• Interphase is the stage in the life cycle of a cell where the cell grows and DNA is replicated.
• the phases of interphase are:
  • G1: the cell is growing
  • S: the cell is replicating its DNA
  • G2: the cell is creating the other parts of the cell like the Golgi body
• Mitosis (2n) – asexual reproduction.
• The two phases of meiosis are Meiosis I - 2 (n), Meiosis II - 4 (n) – sexual reproduction, reduction division.
• Mitosis maintains the chromosome number, and makes haploid cells from a diploid cell. Its Role in the human body is Sexual reproduction and reduction division.

Mitosis vs Meiosis

• Crossing Over occurs in Meiosis I – Prophase I.
• It's the exchange of DNA between paired homologous chromosomes (one froem each parent) that occurs diring egg and sperm (meiosis).
• It leads to genetic variation.
• Homologous chromosomes have the same length, shape, and set of genes. Gametes with many different assortments result from this.
• Gametes are specialized reproductive cells that carry half the genetic material of an organism, and are crucial for sexual reproduction.
• Gametes are prodcued during meiosis during Metaphase 1.
• Metastasis is the development of secondary malignant growths at a distance from a primary site of cancer.
• Malignant Cancer can spread cancer cells throughout one's body through the blood or lymphatic system, and is also known as metastasis with occurs because of uncontrolled growth.
• A Tumor is a swelling of a part of the body caused by tissue growth
• Benign vs Malignant
• A tumor can be either
• An Oncogene is a gene which in certain circumstances transforms a cell into a tumor.
• Tumor suppressor genes represent the opposite side of cell growth control, normally acting to inhibit cell proliferation and tumor development
• Autosomal dominant alleles are expressed in homozygotes and herterozygotes.
• Autosomal recessive is expressed only in homozygotes
• Exmples of Autosomal dominant disorders are: Achondroplasia inheritance & Tay-Sachs Disease
• Alleles on the X chromosome are inherited and differently in males and females
• Males can not transmit X-linked alles to their songs while females pass X-linked alleles to male and femal offspring
• Color Blindness is x-linked
• Polyploidy has three or more of each type of chromosome, and Nondisjunction is the failure of chromosomes to sperate normally in meiosis / mitosis
• Examples of sex chromosome abnormalities:
  • Klinefelter Syndrom in Males & XXX Syndrom in Females
• Down syndrome is a Nondisjunction leading to trisomy 21 increases with age of the mother

Chapter 10 Key Terms

• Genotype - The particular set of alleles carried by an individual
• Phenotype - An individual's observable traits
• Homozygous - Same allele of a gene
• Heterozygous - Different alleles of a gene
• Dominant - Allele that masks the effect of a recessive allele
• Recessive - Allele with an effect that is masked by a dominant allele
• Monohybrid Cross - Cross between two individuals identically heterozygous for alleles of one gene ex. (Aa x Aa) (2x2)
• Dihybrid cross - Cross between two individuals identically heterozygous for alleles of two genes ex. (AaBb x AaBb) (4x4)
• Punnett square - Used to predict the genotypic and phenotypic outcomes of a cross
• Incomplete Dominance - Condition in which one allele is not fully dominant over another, so the heterozygous phenotype is intermediate between the two homozygous phenotypes
• Codominance - Two alleles that are both fully expressed in heterozygous individuals
• Polygenic inheritance - Inheritance in which multiple genes affect one trait
• Pleiotropy - Inheritance pattern in which a single gene affects multiple traits
• Continuous Variation - Range of small differences in forms of a trait
• Bell Curve - Bell shaped curve
• Short Tandem Repeat - Region in which a sequence of a few nucleotides is repeated multiple times in a row
• Pedigrees - Shows whether a trait is associated with a dominant or recessive allele; also shows whether a trait is on an autosome or sex chromosome
• Nondisjunction - Failure of chromosomes to separate properly during mitosis or meiosis
• Polyploidy - Having three or more of each type of chromosome characteristic of the species
• Aneuploidy - Having too many or two few copies of a particular chromosome

Genetics

• Mendel established principles of inheritance and his experiments used pea plants
• Homo = Same so Homozygous have identical alleles of a gene
• Heterozygous have two different alleles of a gene Dominant alleles mask that of a recessive allele paired with it
• Genotypes are a set of alleles carride by an individual - Phenotype is individual obervable traits
• Genotypes are a set of alleles carried by an individual where as a phenotype is individual observable traits
• Mono= One Monohybrid Cross show the probability of the genotype ratio 3:1 where Dihybrid Cross shows the probability of the genetype ratio 9:3:3:1 Dihybride is two genes of diffrent alleles crossed
• Codominance refers to two alleles that both are fully expressed in heterozygous individuals
• Incomplete dominance is one alle where only one allele is not fully dominat over another.
• Polygenic inheritance refers to the inheritance of a trait goverened where more than one gene affect one trait
• Examples are: Skin colour & Height
• Pleotropic is Single gene influencing multiple traits
• Examples are: Sickel Cell Anemia + Cystic Fibrosis and Marfan Syndrome where caused by continmous variation
• Pedigrees shows if assiciated with Dominant/Recessive
• Alleles on the 22nd chromsome show that the 23rd may be an issue of the sex chromosome
• Autosomal domiant alwayss is expressed in the homo/hetrozygotic alles
• recessive can only b eonly expressed on homo
• males can not transmit x-linked alleds to their sons
• the fialure of Chromosomes is from Polyploidy or Nondisjunction

Key terms of chapter 7 include clones, SCNT, and differentiation. Other terms include DNA sequence, histones, chromosomes, centromere and chromatids. Also defined are diploid and chromosome number.