View
- Term
- Definition
- Both Sides
Study
- All (44)
Shortcut Show
Next
Prev
Flip
BIOL 1107: Test 4
heredity |
transmission of traits from one generation to the next |
Genes |
*coded information that specifies specific traits
*specific DNA sequences tell cells to make enzymes and proteins that lead to different traits
*located along chromosomes and can be tagged with dye |
Gametes |
reproductive cells (egg and sperm) that transmit genes to the next generation |
somatic cells |
*other body cells besides gametes
*each species has a certain number of chromosomes in somatic cells; humans have 46 (23 from each parent) |
diploid |
cells with 2 copies of each chromosome (2n) |
haploid |
cells with only one copy of each chromosome (n) |
locus |
the location of a specific gene on a chromosome |
Asexual reproduction |
one parent produces offspring that are exact genetic copies of the parent |
sexual reproduction |
*two parents produce offspring that have a unique combination of both parents' genes
*offspring are different from the parents and each other |
karyotype |
ordered display of all the chromosomes |
Homologs or Homologous chromosomes |
genes that are the same length, etc. and carry genes controlling the same traits |
sex chromosomes |
*X and Y chromosomes
*females have XX, males have XY |
Autosomes |
chromosomes other that sex chromosomes |
fertilization |
*when sperm and egg join and their nuclei fuze
*2 haploid cells -> diploid |
zygote |
Fertilized egg, diploid cell |
Meiosis |
*Special cell division that produces haploid sperm and eggs
*only diploid cells undergo meiosis
*involves duplication of chromosomes and two cell divisions: meiosis I and II
*produces 4 haploid daughter cells |
Meiosis I |
*homologous chromosomes separate
*crossing over
*ends with 2 haploid cells, each chromosome is still 2 sister chromatids |
Prophase I |
*chromosomes condense and homologs become physically connected
*crossing over happens
*spindles form and nucleus is disassembled |
Crossing over |
*the exchanging of DNA segments between non sister chromatids
*makes recombinant chromosomes that carry genes from both parents
*1-3 crossovers happen per chromosome pair in humans
*recombinant chromatids can be oriented different ways in metaphase II and assort independently again
*the further 2 genes are from each other on the chromosome the more likely it is that they will cross over and recombine
*component of genetic variation |
Metaphase I |
homologous chromosomes line up along the center |
Anaphase I |
homologous chromosomes separate and move to poles |
Telophase I and cytokinesis |
*2 haploid cells form
*each chromosome is still 2 sister chromatids |
Meiosis II |
*sister chromatids separate
*4 genetically distinct haploid daughter cells are formed |
Prophase II |
spindle forms |
Metaphase II |
*chromosomes line up in the center
*chromosomes are not identical because of crossing over in meiosis I |
Anaphase II |
Sister chromatids move to poles |
Telophase II and cytokinesis |
*nuclei reform
*chromosomes de-condense
*4 genetically distinct haploid daughter cells are formed |
Alleles |
different versions of a gene |
Independent Assortment of chromosomes |
*homologous chromosomes are oriented randomly in metaphase I
*the maternal chromosome and parental chromosome could be pulled to either pole of the cell
*number of possibilities is 2^n
*component of genetic variation |
Random fertilization |
*any combination of genes in a sperm can fertilize an egg with any possible combination of genes
*component of genetic variation |
Fitness |
*producing offspring
*individuals with combinations of genes best suited to their environment are more likely to survive and reproduce and thus pass those genes on: survival of the fittest |
traits |
*variants on a characteristic
*studied by Mendel |
True breeding plants |
*with self pollination, it produces the same variety as the parent plant over and over
*P is used to refer to the true breeding parents, and F1 is used to me the first generation of offspring, F2 for the next, and so on
*This is the reason why Mendel's studies had such success |
Dominant and recessive traits |
*Dominant traits appear to cover up recessive ones when one dominant and one recessive allele are inherited and when two dominant alleles are inherited
*recessive traits appear when two recessive alleles are inherited
*dominant traits are dominant because they code for enzymes or proteins that control a trait. Either it's present or it isn't, if it's present, the dominant trait is displayed
*a dominant trait isn't necessarily the most common in a population |
Law of Segregation |
*the two alleles for a characteristic segregate (separate) during formation of gametes and end up in different gametes
*an egg or sperm only gets 1 of the 2 alleles for a trait that end up in the diploid cell |
heterozygous |
having two different alleles for a trait |
homozygous |
having 2 of the same allele for a trait |
phenotype |
an organism's appearance or observable trait |
genotype |
and organism's genetic makeup |
test cross |
breeding an organism of an unknown genotype with a homozygous recessive organism to determine its genotype |
monohybrid |
heterozygous for the particular characteristic being studied in a cross |
monohybrid cross |
*breeding 2 organisms heterozygous for a trait
*leads to a 3:1 dominant to recessive phenotypic ratio |
Dihybrid |
heterozygous for 2 characteristics being studied in a cross |
dihybrid cross |
*breeding 2 organisms heterozygous for the 2 traits being studied
*leads to a 9:3:3:1 phenotypic ratio (dominant & dominant; dominant & recessive; recessive & dominant; recessive & recessive) |