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intro to genetics
biol 1210
| Question | Answer |
|---|---|
| name the monomers & polymers of nucleic acids & 2 types of nucleic acids | monomers: nucleotides, polymers: polynucleotides, nucleic acids: Deoxyribonucleic acid (DNA) & ribonucleic acid (RNA) |
| describe basic structure of a nucleotide | nitrogenous base + pentose (5-carbon carbohydrate ring) + phosphate group |
| 2 families of nitrogenous bases & which bases r included in each | pyrimidines (cytosine, thymine, uracil) have single 6-membered ring; purines (adenine & guanine) have 6-membered ring fused to 5-membered ring. Longer name = smaller base |
| DNA v. RNA structural differences | DNA: 2 strands, bases CTAG, deoxyribose sugar, RNA: 1 strand, bases CUAG (uracil replaces thymine), ribose sugar |
| difference between deoxyribose & ribose | *deoxy*ribose = decrease in O. In organic molecules, O is polar/more electronegative = more reactive. Ribose is bonded to -OH at 2' while deoxyribose is only bonded to H at 2'. Therefore, DNA is more stable (less reactive) than RNA |
| phosphodiester linkages | the covalent bonds that link nucleotides between -OH group on 3' carbon of 1 nucleotide & phosphate group on the 5' carbon of the next. The bonds are formed by dehydration synthesis & build sugar/phosphate backbone for the nitrogenous bases |
| what do 3', 5' and other #' mean on a polynucleotide? | refers to a carbon's position on the pentose ring of a nucleotide. 3' = 3rd carbon from O at top of ring, 5' = 5th carbon from O |
| in which direction are nucleic acids synthesized? | polynucleotides bond in the 5' to 3' direction where the 5' end of a nucleotide has the previous nucleotide's phosphate group bonded to its sugar at 5', and the 3' end of a nucleotide has the next nucleotide's phosphate group bonded to its sugar at 3' |
| which end of a polynucleotide is 'open'? | 3' end at the hydroxyl group on the sugar |
| what kind of bond holds nitrogenous bases together in DNA? Which are complementary bases & why | hydrogen bonds. Because of their shapes, bases must pair up a pyrimidine to a purine to fit in the double helix. These complementary bases are T & A (2 hydrogen bonds) and C & G (3 hydrogen bonds) |
| describe double helix structure (incl. directions) | hydrogen bonds between complementary bases only form if the strands are antiparallel to each other (one is 5' -> 3', other is 3' -> 5'). DNA molecule has 2 polynucleotides spiraling around imaginary axis (influenced by hydrogen bonds) = double helix |
| if the nitrogenous bases in the DNA of a snail is found to consist of 20% guanine, determine % of thymine, cytosine and adenine | 100% nitrogenous bases: 20% G = 20% C, 100%-40% = 60% made of 30% T + 30% A. In any sample of DNA from any organism, the # of purines = the # of pyrimidines |
| 3 major types of RNA | mRNA - messenger (copy of DNA sent to ribosome), tRNA - transfer (bring amino acids to form protein), rRNA - ribosomal (part of ribosome subunit) |
| why is DNA, rather than RNA, used for long-term info storage in cells? | Bc DNA is more stable (less reactive) than RNA. It is structured from 2 strands of polynucleotides that wrap around each other and have nucleotides containing deoxyribose |
| central dogma | summarizes the flow of information in cells. DNA -> RNA -> proteins: DNA sequence codes for mRNA sequence, mRNA codes for amino acid sequence |
| genes | a section of DNA that codes for a specific RNA (therefore codes for proteins) |
| DNA replication | the process of using a DNA template to make a new complementary DNA strand. Occurs in nucleus |
| transcription | using a DNA template to make a complementary RNA (mRNA). One of 2 DNA strands (template) orders sequence of nucleotides in RNA transcript. Occurs in nucleus |
| translation | using info in mRNA to synthesize proteins. mRNA base triplets (codons) are read in 5' to 3' direction; each codon specifies 1 of 20 amino acids to be placed at corresponding position along a polypeptide (3 bases:1 codon:1 amino acid) |
| genotype v. phenotype | sequence of bases in an organism's DNA v. the product of proteins an organism makes |
| allele & proteins | different versions of the same gene (differ in DNA sequence). Proteins produced by different alleles of same gene often differ in amino acid sequence. |
| chromosome v. chromatin | long double helix of DNA wrapped around proteins (histones) present before cell division starts. Made up of compacted chromatin (usually loosely packed DNA & proteins that sits in the nucleus during rest of cell's life) |
| # of chromosomes does not differ between species. T/F | F. Every species has a characteristic # of chromosomes |
| DNA's role in a cell | DNA encodes the cell's genetic information. Genes determine what proteins the cell makes & therefore all of its cellular functions |
| describe structure of chromosome | chromosomes consist of chromatid(s). Unreplicated chromosome has 1 chromatid while a duplicated chromosome has 2 sister chromatids. |
| chromosome before cell division & mitosis | Before cell division starts, chromosomes are replicated as long strands of DNA. Before mitosis starts, chromatids are attached along entire length by cohesins; during, attached only at centromere & compacted into shape. |
| homologs | aka homologous chromosomes, chromosomes of the same length, centromere position & staining pattern for genes of the same characters. In 2n cell, 1 homolog from mother, 1 homolog from father |
| homologous pair | pair of homologs that contain the same genes in the same position along the chromosome but are NOT always identical (may contain different alleles). |
| sex chromosomes v. autosomes | sex chromosomes: determine the sex of the individual (in most mammals, females have 2 X chromosomes, males have an X & Y). Autosomes: non-sex chromosomes (code for everything else!). |
| karyotype | identifies the # and types of chromosomes present in a species |
| diploid & diploid # for humans | many organisms (incl. humans). Diploids have a pair of homologs of each chromosome & 2 alleles of each gene. Humans diploid # is 23 (46 chromosomes). |
| haploid | organisms that have 1 of each type of chromosome and 1 allele of each gene |
| haploid # (n) | indicates the # of distinct types of chromosomes present (sex chromosomes are a single type. Haploid # for humans = 23 |
| ploidy | indicates the # of complete chromosome sets a cell contains |
| n cells v. 2n cells - what types of cells | n: 1 set of chromosomes - gametes, gametophytes & spores. 2n: paternal chromosome & maternal chromosome (2 sets of chromosomes) - all other body cells |
| polyploid | organisms/cells w 3+ versions of each type of chromosome (3n, 4n, etc.) |
| describe the sexual life cycle of a human | multicellular (2n = 46) adults -> meiosis -> haploid gametes (n = 23, egg & sperm) -> fertilization -> diploid zygote (2n = 46) -> mitosis & development -> adults etc. |
| functions of 2 forms of cell division | mitosis - production of identical cells for growth & repair or asexual reproduction; produces 2 diploid cells. Meiosis - production of gametes (animals) or spores (plants) that are haploid & genetically different; produces 4 haploid cells |
| heredity | aka inheritance, the transmission of traits from one generation to the next. |
| DNA, genes & chromosomes roles in heredity | traits are derived from the types of proteins an organism makes & DNA is made of genes that code for specific proteins. Chromosomes are replicated before meiosis to form genetically unique offspring that have traits passed on from their parents |
| chromosome complement | the # of chromosomes characteristic of any typical body cell of any member of a species |
| somatic cell v. gamete | a somatic cell is usually 2n & makes up the majority of an organism's body cells while a gamete is n & are genetically unique cells produced from meiosis and used in sexual reproduction to form genetically varied offspring |
| compare/contrast mitosis & meiosis by the # of stages, # of daughter cells produced & ploidy of the daughter cells | mitosis & meiosis both have 4 stages; mitosis = 2 diploid daughter cells, meiosis = 4 haploid daughter cells |
| difference btwn mitosis & cytokinesis | mitosis: involves the alignment, split and movement of duplicated chromosomes to the poles of the cell. Cytokinesis: happens afterwards, splits the cytoplasm into two to make 2 cells |
| cell division in unicellular v. multicellular organisms | unicellular: cell division is basis of reproduction & happens by mitosis (asexually) for most; multicellular: uses mitosis for growth/repair or sometimes asexual reproduction, meiosis for sexual reproduction |
Created by:
AntBanana
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