Chapter 13 Flashcards
Order inside (box)
DNA, Gene, Chromosome, Genome
Genome
complete complement of an organism’s DNA
includes: genes (control traits), non-codng DNA organized in chromosmes
Genes
“unit of heredity”, made up of segments of DNA
Eukaryotic DNA is organized in chromosomes
have specific places on chromosomes (locus)
Introns
non-coding sequences. do not produce a protein
Exons
coding-sequences. produces a protein
Chromosome theory of heredity
chromosomes carry genes
Asexual Reproduction
many single-celled organisms reproduce by splitting, budding, parthenogenesis
some multicellular organisms can reproduce asexually, product clones
Asexual vs. sexual reproduction
Asexual: clone, mitosis
Sexual: 2 parents, offspring genetically different from parents and each other, fusion of 2 gamete to produce a single zygote, allows genetic recombination
Zygote
embryo, diploid, 2 copies of chromosomes
Karyotype
ordered display of an individual’s chromosomes
Trisomy
3 chromosome 21’s, Down’s Syndrome
Homologous pairs
In diploid autosomes, chromosomes are in ?
when 2 non-sister chromosomes become close
Autosomes
non-sex chromosomes
Gametes
in humans:
contain 22 autosomes and 1 sex chromosome
haploid
sperm or egg
produced by meiosis
fertilization/syngamy
results in zygote that is now diploid
Reduction division
chromosome number is halved, meiosis
Sister chromatid
duplicated form of replicated chromosome
centromere
where chromosomes are attached
Independent assortment
2n number of possibilities
Life cycle
sequence of stages in organism’s reproductive history; conception to reproduction
somatic cells
only cell other than gametes (most cells in body)
More genetic diversity equals
more potential for survival of species when environmental condtions change
shuffling of genes in meiosis
crossing-over in meiosis
fertilization: combines genes from 2 separate individuals
DNA back-up and repair
- asexual organisms don’t have back-up copis of genes
- sexual organisms have 2 sets of chromosomes and 1 can act as a back-up if the other is damaged
- sexual mechanisms, especially recombination, are used to repiar damaged DNA - the undamaged chromsom acts as a template and eventually both chromosomes end up with correct gene
Mitosis vs. Meiosis
DNA replication
of divisions
Synapsis of homologous chromosomes
of daughter cells and genetic composition
Role in animal body
Mitosis vs. Meiosis
DNA Replication: During interphase before nuclear division begions - during interphase before meiosis 1 begins (once
# of Divisions: one - two
Synapsis of homologous chromosomes: doesn’t happen - prophase 1, homologous chromosomes join along their lenth, forming tetrads (grops of 4 chromosomes); synapsis is associated with crossing-over between non-sister chromatids
# of daughter cells and genetic composisiton: 2 diploid (2n) genetically identical to parent - 4, haploid (n), have 1/2 as many chromosomes as parent cells, genetically non identical to parent and each other
Role in animal body: Enables multicellular adult to arise from zygote; prodcues cells for growth and tissue repair - produces gametes; reduces chrmosome number by half and introduces genetic variability among gametes
