Review 4 Flashcards
Know the parts and shape of DNA
A molecule of DNA consists of two strands and looks like a spiraling ladder, “double helix”. The “side” are molecules of deoxyribose sugar and phosphate. The “Rungs” are a series of paired nitrogen bases. Remember phosphate, sugar, and base.
Know what DNA codes for.
DNA codes for RNA which tells cells which protein to make in which order
Know the base pairing rules.
In DNA: Adenine to Thymine A-T Guanine to Cytosine G-C In RNA: Adenine to Uracil A-U Guanine to Cytosine G-C
What’s the difference between DNA and RNA?
RNA is a single stranded DNA is Double stranded (each strand serves as a template for building a new partner)
RNA uses ribose instead of deoxyribose sugar
RNA uses a nitrogenous base uracil U instead of thymine T
What is mRNA and tRNA?
tRNA (transfer RNA) carries an amino acid to ribosome using the mRNA coding sequence.
3 base on mRNA is a codon
3 base on tRNA is an anticodon
Know the “Central Dogma”.
The central dogma of molecular biology explains that DNA codes for RNA, which codes for proteins. DNA is the molecule of heredity that passes from parents to offspring. It contains the instructions for building RNA and proteins, which make up the structure of the body and carry out most of its functions.
DNA using transcription to RNA using translation to protein
Know the steps in protein synthesis where they occur in the cell.
Transcription occurs in the nucleus
Translation occurs in the cytoplasm
Know how to get from DNA to codon to amino acid.
- DNA in the nucleus is separated by an enzyme and serves as a template to build RNA (transcription)
- RNA that is built is called mRNA and is transported out of the nucleus
- In the cytoplasm, at ribosomes, translation occurs
- Codons, sets of 3 nucleotides, are read from the mRNA and matched to the anticodon, set of 3 nucleotides of tRNA, which carry a specific amino acid.
- Based on the order of the codons, amino acids are linked together in a specific order to form proteins.
What are the mutations we discussed?
Point mutation-occur when one nucleotides is substituted for another.
Nonsense mutation-creates an early STOP codon in the middle of the gene
Frame shift mutation-occurs when nucleotides are inserted or deleted, shifting the codons that are “read” during translations.
What is cancer?
Cancer occurs when cells in the body divide out of control. Mutation in the genes that control cell division result in cancer.
What is polygenic and pleiotropic?
Polygenic traits are determined by more than one genes. They tend to show more of a continuum than traits determined by a single gene. Example eye, skin color and height.
Pleiotropic occurs when a single gene affects more than one trait. Example sickle cell anemia
Know the 7 lines of evidence for evolution, what they mean, and some examples.
- Artificial selection- fact that we can personally alter organisms to have “better” traits.
- Similarities in body structure example human, cat, whale, bat arm structure/vestigial organs
- DNA and molecular evidence-similar DNA sequences in related species
- Patterns of development Example fetus turtle, human, chick, pig
- Hierarchical organization of living things-nested groups or “groups within groups”
- Biogeography –study of how species are distrusted on Earth and Organisms evolved in a certain place and then left descendants in the places where they were able to spread.
- Fossils- allows us to “witness” gradual changes in organism or extremely large portions of time.
What is natural selection and how does it work? How is it different than Lamarck’s version of evolution?
- Natural selection-in any population individual have many trait variation-traits are least partly by genes are heritable, passed from parents to offspring-organisms that poses variable heritable traits that are advantageous leave more offspring than those without the advantageous traits-Advantageous traits become more common in a population resulting in adaptation.
- Lamarck’s version-believed that organisms acquired new traits over their life time and then passed these traits to their offspring he called tis the inheritance of acquired characteristics
What are adaptations?
Adaptation are traits that make organisms well suited to living and reproducing in their environments.
What are homologous and vestigial structures?
- Homologous- the similarity in the body structure in many different species from the same lineage suggest that all animals have been modified from one ancient common ancestor.
- Vestigial-these are trace homologues that are greatly reduced in size and no longer serve their original intended function. They further show modification through time. (examples include: “tail bone” in humans, remnants of hind legs in snakes)
