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85 Cards in this Set
- Front
- Back
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Gametogenesis
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Requires both Mitosis and Differentiation
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Cleavage
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the early cell divisions of embryos, in which little or no growth occurs between divisions; reduces the cell size and distributes gene-regulating substances to the newly formed cell
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Gastrulation
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the process whereby a blastula develops into a gastrula, including the formation of endoderm, ectoderm, and mesoderm
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Organogenesis
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the process by which the layers of the gastrula(endoderm, ectoderm, mesoderm) rearrange to form organs
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Larva
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an immature form of an animal that subsequently undergoes metamorphosis into its adult form; includes the caterpillars of moths and butterflies, the maggots of flies, and the tadpoles of frogs and toads
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Direct vs. Indirect Development
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Indirect- offspring undergo radical changes in body form between birth and sexual maturity
• this is metamorphosis -Direct- at birth the offspring have the same body form as adults |
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Adult
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Sexually mature and can produce gametes
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Regulation of Development
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localization of maternal molecules
• uneven distribution of RNA and proteins -Cell signaling -Gene regulatory networks • collection of DNA segments within a cell that interacts with each other or within protein products of each other to regulate the rate the genes in the network are transcribed |
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The Human Life Cycle
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-Gametogenesis
• in ovaries and testes -Fertilization • internal -Cleavage • within the uterine tube • proliferation of cells without growth • takes place within the fallopian tube • In humans it begins to separate two major different groups of cells o Inner cell mass- gives rise to the embryo proper • These are the embryonic stem cells o Outercell layer • Profoblast -Gastrulation -Organogenesis |
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Facts About Drinking in Pregnancy
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-Readily crosses the placenta
-Alcohol is toxic to the fetus- a teratogen -Preventable cause of intellectual disabilities -Can cause Fetal Alcohol Syndrome and other alcohol-related conditions -8 times more likely to have a baby die of SIDS if binge drinking during the first trimester or in 3 months prior to pregnancy occurs |
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Fetal Alcohol Syndrome
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a cluster of symptoms, including mental retardation and physical abnormalities, that occur in infants born to mothers who consume large amounts of alcoholic beverages during pregnancy
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Allantois
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Stores waste
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Chorion
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Acts as a respiratory surface, provides for the exchange of gases, nutrients and wastes
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Amnion
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Encloses the embryo in fluid
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Yolk sac
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Helps absorb nutrients from the mother,contains yolk as food
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Blastocyst
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an early stage of human embryonic development, consisting of a hallow ball of cells, enclosing a mass of cells attached to its inner surface, which becomes the embryo
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Blastula
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in animals, the embryonic stage attained at the end of cleavage, in which the embryo usually consists of a hallow ball with a wall that is one or several cell layers thick
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Blastopore
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the site at which a blastula indents to form a gastrula
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Ectoderm
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the outermost embryonic tissue layer, which gives rise to structures such as hairs, the epidermis of the skin, and the nervous system
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Endoderm
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the innermost embryonic tissue layer, which gives rise to structures such as the lining of the digestive and respiratory tracts
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Gastrula
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in animal development, a three-layered embryo with ectoderm, mesoderm, and endoderm cell layers. The endoderm layer usually encloses the primitive gut
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Mesoderm
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the middle embryonic tissue layer, lying between the endoderm and ectoderm, and normally the last to develop; gives rise to structures such as muscles, the skeleton, the circulator system, and the kidneys.
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Morula
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in animals, an embryonic stage during cleavage, when the embryo consists of a solid ball of cells
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What are the units of heredity?
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• Genes and alleles from parents DNA
• Genotype codes for phenotype o Morphology o Physiology o Behavior • Specific alleles come from parents |
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DNA Structure Reflects its Role as the Genetic Material
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• Eukaryotic DNA observed in cell nucleus and condensed chromosomes
• DNA twice as abundant in diploid cells as haploid cells • DNA doubles during S phase of cell cycle • Shows same patterns of transmission as genetic information it carries |
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DNA in Chromosomes
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1. DNA Double helix
2. DNA wound around histone proteins 3. Coiled DNA/histone beads 4. Loops attached to a protein scaffold; this stage of partial condensation typically occurs in a nondividing cell 5. Folded chromosome, fully condensed in a dividing cell |
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What is the structure of DNA
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DNA consists of four small subunits of nucleotides. Each nucleotides in DNA has three parts: a phosphate groups, a sugar deoxyribose, and one of four nitrogen-containing bases: adenine, guanine, thymine, cytosine.
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DNA nucleotide
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a subunit of which nucleic acids are composed; a phosphate group bonded to a sugar (deoxyribose in DNA), which is in turn bonded to a nitrogen-containing base (adenine, guanine, cytosine, or thymine in DNA). Nucleotides are linked together, forming a strand of nucleic acid, by bonds between the phosphate and one nucleotide and the sugar of the next nucleotide
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3 Ways of getting DNA in Bacteria
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1) conjugation
2) transduction- viruses can insert DNA 3) transformation |
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DNA Replication
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the copying of the double-stranded DNA molecule, producing two identical DNA double helices.
DNA replication involved three major actions. First, the DNA double helix must be opened up so the base sequence can be read. Then, new DNA strands with base sequences complementary to the two original strands must be synthesized. In eukaryotic cells, these new DNA strands are synthesized in fairly short pieces. Therefore, the third step in DNA replication is to stick the pieces together to form a continuous new strand of DNA. Each step is carried out by a distinct set of enzymes |
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Enzyme required for DNA replication
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DNA Helicase- an enzyme that helps unwind the DNA double helix during DNA replication
DNA Polymerase- an enzyme that bonds DNA nucleotides together into a continuous strand, using a preexisting DNA strand as a template |
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Semiconservative Replication
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- the process of replication of the DNA double helix the two DNA strands separate, and each is used as a template for the synthesis of a complementary DNA strand. Consequently, each daughter double helix consists of one parental strand and one new strand
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How do mistakes happen during replication?
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Mutations
Are rare Is actually a “proof reading” system that catches most errors (DNA repair enzymes) Specificity of hydrogen bonding between complementary base pairs makes replication quite accurate DNA polymerase incorporates incorrect bases about 1/000 to 1/100,000 base pairs! BUT completed DNA strands contain only about one mistake in every 100 MILLION to 1 BILLION base pairs Ex. Humans – usually less than one per chromosome Can be neutral, beneficial or harmful |
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Deletion Mutation
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A nucleotide pair is deleted
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Insertion Mutation
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A nucleotide is inserted
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Inversion Mutation
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A DNA segment is inverted
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Nucleotide Substitution
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A Nucleotide pair changes example from A-T to T-A
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Point Mutation
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A mutation in which a single base pair in DNA has been changed
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Translocation
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When DNA segments are switched
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DNA Ligase
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an enzyme that bonds the terminal sugar in one DNA strand to the terminal phosphate in a second DNA strand, creating a single strand with a continuous sugar-phosphate backbone
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One Gene- One Protein
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Most genes contain info to direct synthesis of a single protein
• proteins form many cellular structures • enzymes that catalyze cell reactors -How does information flow from DNA to protein? • DNA → nucleus • Protein synthesis occurs on ribosomes in cytoplasm |
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Messenger RNA
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-carries DNA gene information to ribosomes
-carries the information for the amino acid sequence of a proteins; groups of these bases (codons), specify the amino acids a strand of RNA, complementary to the DNA of a gene, that conveys the genetic information in DNA to the ribosomes to be used during protein synthesis; sequences of three bases (codons) in mRNA that specify particular amino acids to be incorporated into a protein |
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Ribosomal RNA
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-carries out translation
-2 subunits remain separate, only come together during protein synthesis, job is to close mRNA a type of RNA that combines with proteins to form ribosomes |
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Transfer RNA
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-20 enzymes in cytoplasm
-1 for each amino acids -enzymes recognized the transfer RNA and use energy (ATP) to attach the correct amino acid a type of RNA that binds to a specific amino acid, caries it to a ribosome, and positions it for incorporation into the growing protein chain during protein synthesis. A set of three bases in tRNA (the anticodon) is complementary to the set of three bases in mRNA (the codon) that codes for that specific amino acid in the genetic code |
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Transcription
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the synthesis of an RNA molecule from a DNA template
Transcribe- to make a written copy of something in the same language • Transcription of the gene produces an mRNA with a nucleotide sequence complementary to one of the DNA strands |
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Transcription Initiation
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• RNA polymerase binds to the promoter region of DNA near the beginning of a gene, separating the double helix near the promoter
• 3’ to 5’ • promoter is not transcribed |
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Transcription Elongation
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• RNA polymerase travels along the DNA template strand, unwinding the DNA double helix and synthesizing RNA by catalyzing the addition of ribose nucleotides into an RNA molecule. The nucleotides in the RNA are complementary to the template strand of the DNA
• 3’ to 5’ |
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Transcription Termination
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• At the end of the gene, RNA polymerase encounters a DNA sequence called a termination signal. RNA polymerase detaches from the DNA and releases the RNA molecule
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Conclusion of Transcription
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• After termination, the DNA completely rewinds into a double helix. The RNA molecule is free to move from the nucleus to the cytoplasm for translation, the RNA polymerase may move to another gene and begin transcription once again
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Start Codon
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AUG
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Stop Codon
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UAA, UAG, UGA
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Messenger RNA Synthesis in Prokaryotes
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Prokaryotic genes are typically compact. All the nucleotides of a gene code for the amino kids in a protein. A prokaryotic cell commonly transcribe a single, very long mRNA from a series of adjacent genes. Because prokaryotic cells do not have a nuclear membrane separating their DNA from the cytoplasm, transcription and translation are usually not serrated, either in space or time. mRNA molecule begins to separate from the DNA during transcription, ribosomes immediately begin translating the mRNA into protein.
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Messenger RNA Synthesis in Eukaryotes
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A.Eukaryotic genes consists of eons, which code for the amino acid sequence of a protein, and introns, which do not.
Transcription of a eukaryotic gene produces a very long RNA strand which starts before the first exon and ends after the last exon. More nucleotides are added at the beginning and end of this pre-RNA molecule, forming a "cap" and "tail". These nucleates help to move the finished mRNA through the nuclear envelope to the cytoplasm, to bind the mRNA to a ribosome, and to prevent cellular enzymes from breaking down the mRNA molecule. To convert this pre-mRNA molecule into the finished mRNA, enzymes in the nucleus cut the pre-mRNA apart at the junctions between introns and eons, splice together the preteen-coding eons, and discard the introns. The finished mRNA molecules then leave the nucleus and enter the cytoplasm through pores in the nuclear envelop. In the cytoplasm the mRNA binds to ribosomes, which synthesize protein specified by the mRNA base sequence 1. Transcribing the gene into a long pre mRNA molecule 2. Adding additional RNA nucleotides to form the cap and tail 3. Cutting out the introns and splicing the eons together into the finished mRNA 4. Moving the finished mRNA out of the nucleus into the cytoplasm for translation |
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Translation
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converting words from one language into another language
• Translation of the mRNA produces a protein molecule with an amino acid sequence determined by the nucleotide sequence in the mRNA |
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Translation Initiation
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• 1. A tRNA with an attached methionine amino acid binds to a small ribosomal subunit, forming a preinitiation complex
• 2. The preinitiation complex binds to an mRNA molecule. The methionine (met) tRNA anticodon (UAC) base-pairs with the start codon (AUG) of the mRNA • 3. The large ribosomal subunit binds to the small subunit. The methionine tRNA binds to the first tRNA site on the large subunit |
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Translation Elongation
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• 4.The second codon of the mRNA (GUU) base-pairs with the anticodon (CAA) of the second tRNA carrying the amino acid valine (val). This tRNA binds to the second tRNA site on the large subunit
• 5.The catalytic site on the large subunit catalyzes the formation of a peptide bond linking the amino acids methionine and valine. The two amino acids are now attached to the tRNA in the second binding site • 6. The “empty” tRNA is released and the ribosome moves down the mRNA, one codon to the right. The tRNA that is attached to the two amino acids is now in the first tRNA binding site and the second tRNA binding site is empty • 7. The third codon of mRNA (CAU) base-pairs with the anticodon (GUA) of a tRNA carrying the amino acid histidine (his). This tRNA enters the second tRNA binding site on the large subunit • 8. The catalytic site forms a peptide bond between valine and histidine, leaving the peptide attached to the tRNA in the second binding site. The tRNA in the first site leaves, and the ribosome moves one codon over on the mRNA |
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Translation Termination
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• 9. This process repeats until a stop codon is reached; the mRNA and the completed peptide are released from the ribosome, and the subunits separate
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What causes mistakes in DNA replication
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-Ultraviolet radiation-sunlight and tanning beds
-Cigarette smoke- environmental smoke • causes mutations in a gene called RAS, it is associated with many human cancers • more than 30 % of lung cancer, 90 % of pancreatic cancer, 50% of colon cancers are due to mutations on the RAS gene |
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How Do Mutations Affect Protein Function? Inversion and Translocation
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-Can be benign (no problem)
-This happens if entire genes including their promoters get broken apart and reattached -Not benign -Happens when a gene is split in two |
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How Do Mutations Affect Protein Function? Deletion and Insertion
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-3 nucleotides code for one amino acid so if you delete or add 3 nucleotides, it may not alter the protein function
-if you delete or insert 1 or 2 nucleotides, that shift the rest of them which results in catastrophic effects because it changes the set of triples -frame shift mutations- when everything shifts by one |
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How do mutations affect protein function? Substitution
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-known as point mutation, one nucleotide replaces another nucleotide
o 4 possible outcomes -1) protein can be unchanged this can happen due to all of the redundancy in the code • UAU→ UAC, both are tyrosine -2) a new protein may be functionally equivalent to the old one neutral mutations -3) protein function might be changed by altered amino acid sequence -4) protein function is destroyed by premature stop codon |
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Why are mutations so important for evolution?
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-They are what give us genetic diversity
-mutations are the raw material for evolution -Natural selections act of these -Human mutation rates • they range from 1/100,000 to 1/1,000,000 gametes • males produce 300-400 million sperm/per ejaculate o each ejaculate contains about 600 sperm with new mutations |
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How are genes regulated?
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-Human genome- 20,000 to 25,000 genes
• in most of your cells • red blood cells do not because they do not have nuclei • not all genes are expressed (transcribed and translated) -Gene expression • some genes are expressed in all cells • others only expressed in very specific cells, or certain point in life, or under specific environmental conditions -Regulation of gene expression • can occur at transcription, translation or protein activity |
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Gene Regulation in Eukaryotes
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There are 3 levels of gene regulation
• regulating of individual genes o promoter regions- contain several different transcription factor binding sites o the presence or absence of these can regulate transcripters • regulation of regions of chromosomes o highly condensed • sometimes so tightly there is no access to RNA polymerase • Regulation of entire chromosome o Most of a chromosome ends up being really condensed and RNA polymerase cannot access it, prevents transcription |
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Why do bruises turn colors?
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-purple→green→yellow
-hit your arm • blood vessels break and release red blood cells, these red blood cells burse open and release their hemoglobin • hemoglobin contains a heme group, the heme group contains iron and this hemoglobin is blueish purple in its deoxygenated state • heme is not a good thing, it is toxic to the liver, kidneys, and brain • hemoxygenase converts heme to billiverdin (green) • a second enzyme comes along and converts billiverden to bilirubin (yellow) • the billibruin is no longer toxic and moves to liver and is excreted into bile |
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Cystic Fibrosis
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CFTR
• channel protein, found in sweat glands, lungs, intestines -Mutation in CFTR • prevents reabsorption of chloride and sodium (salt) • salt stays in sweat • cells that line your airways and lungs have the same CFTR protein • lungs are covered in a thin mucous layer o traps bacteria and debris -Defective CFTR protein • the mucus becomes very dehydrated and becomes thick (rather than thin), the airways become clogged and it is not very efficient in removing bacteria and debris o cannot clear bacteria and get a bad infection |
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Codon
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a sequence of three bases of messenger RNA that specifies a particular amino acid to be incorporated into a protein; certain codons also signal the beginning or end of protein synthesis
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Exon
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a segment of DNA in a eukaryotic gene that codes for amino acids in a protein
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Intron
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a segment of DNA in a eukaryotic gene that does not code for amino acids in a protein
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What is Evolution?
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-Evolution
• Process by which modern organism descended with modification from pre-existing life forms • Changes in allele frequencies in a population (or species) over time -Process of evolution by natural selection • Natural selection is one mechanism that can result in evolution • Natural selection is differential reproduction and survivorship among individuals within a population |
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Analogous Structure
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structures that have similar functions and superficially similar appearance but very different anatomies, such as the wings of insects and birds. The similarities are the result of similar environmental pressures rather than a common ancestry.
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Artificial Selection
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a selective breeding procedure in which only those individuals with particular traits are chosen as breeders; used mainly to enhance desirable traits in domesticated plants and animals; may also be used in evolutionary biology experiments
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Convergent Evolution
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the independent evolution of similar structures among unrelated organisms as a result of similar environmental pressures
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Homologous Structure
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structures that may differ in function but that have similar anatomy, presumably because the organisms that possess them have descended from common ancestors
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Natural Selection
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the unequal survival and reproduction of organisms with different phenotypes, caused by environmental forces. Natural selection refers specifically to cases in which the differing phenotypes are heritable; that is, they are caused at least partly by genetic differences, with the result that better adapted phenotypes become more common in the population
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Vestigial Structure
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a structure that serves no apparent purpose but is homologous to functional structures in related organism and provides evidence of evolution
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Generalist
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Eat a wide range of food
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Specialist
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Eat only one of a few food resources
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Darwins First Postulate
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Variation exists among individuals in a population in the traits they possess.
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Darwins Second Postulate
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The variation in traits among individuals is at least in part heritable. Traits can be passed from parents to their offspring, and so offspring resemble their parents in the traits they possess.
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Darwins Third Postulate
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Traits confer differences in survivorship and reproduction, a measure we call fitness: individuals with certain traits will have higher fitness, while those with other traits will have lower fitness.
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Darwins Fourth Postulate
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The fitness of individuals is not random; it is based on the traits they possess.
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Fruit Fly Tolerance
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ADH+: alcohol resistance
ADH-: cannot process alcohol |
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Ethogram
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Formal description of an animals common behaviors
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Anthropomorphism
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Animal behaviors that we attribute to human motivations, characteristics, or emotions
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