Chapter 1 Flashcards
What is a phenotype?
the observable traits of an organism
What is a genotype?
the genetic constitution of an organism
What is genetic variation?
differences between alleles/in nucleotide sequence
What is an allele?
alternative forms of a gene
What is the Law of Segregation?
Mendel’s contribution that only one of the two gene copies present in an organism is distributed to each gamete (egg or sperm cell) that it makes, and the allocation of the gene copies is random
What is the Law of Independent Assortment?
In Meiosis, when the alleles at separate genes on different chromosomes segregate and sort independently
What are genes?
the physical units of heredity, as originally posited by Mendel; now known to be defined DNA sequences
What are chromosomes?
long molecules of double-stranded DNA wrapped around proteins, which contains genes
What do sexually reproducing organisms usually have?
homologous pairs(or homologs), two of each chromosome, where one homolog comes from each parent
what is produced by meiosis?
reproductive cells, or gametes
What are the 3 domains of life?
- Eukarya (true nucleus, multiple chromosomes)
- Bacteria (no true nucleus, single chromosomes)
- Archaea (no true nucleus, single chromosomes)
What are 5 characteristics of eukaryotic cells?
- multiple chromosomes organized by proteins
- membrane-bound nucleus and intracellular membrane
- membrane-bound organelles
- unicellular and multicellular
- larger genomes
What are 4 characteristics of prokaryotic cells?
- single large chromosome(some also contain plasmids)
- no membrane-bound nucleus or cellular membranes
- unicellular
- smaller genomes
What type of cells contain mitochondria?
plant and animal cells
What type of cells contain chloroplasts?
plant cells
What is the structure of DNA?
double helix with sugar phosphate backbones on the outsides and nucleotide bases arrayed in complementary pairs toward the center
What are DNA Nucleotides composed of?
a deoxyribose(5-carbon) sugar, a phosphate group, and one of 4 nitrogenous bases designated-Adenine, Guanine, Thymine, Cytosine
How are nucleotides linked together?
linked together by a phosphodiester bond between the 5’ phosphate group of one nucleotide and the 3’ hydroxyl of another
What kind of bond forms between complementary base pairs?
hydrogen bonds
What is a characteristic of the two strands of DNA?
they are antiparallel, meaning that the 5’ and 3’ designations of the phosphate and hydroxyl at the ends of the DNA strands establish polarity
What number does meiosis start and end with?
starts with diploid number and ends in gametes with the haploid number of chromosomes(4 distinct gametes produced)
What is Chargaff’s rule?
for most organisms the percentage of adenine and thymine are equal, and the percentage of guanine and cytosine are equal
