UNIT 2- GENETICS Flashcards
sex
biological differences specifically in genitalia/reproductive organs and genetics (XX vs. XY chromosomes)
genotype
your genes/genetic information
phenotype
the outward expression of your genotype/genes
genetics
the study of heredity, variation and how traits are passed from one generation to the next
inheritance
in sexually reproducing organisms, the inheritance of traits determines genetic variation among offspring
why do we need/want genetic variation?
it is necessary for evolution
DNA stands for
deoxyribonucleic acid
what is DNA
genetic code found in all cells
the structure is identical in all plants and animals (double helix)
what makes organisms unique in DNA?
the order of nitrogenous bases in their DNA
genes
segments of DNA that control the expression of a trait
instructions to make one protein
chromosomes
DNA coils to form chromosomes
chromosome numbers vary betw organisms
passed from parent to offspring
haploid
a cell containing a single set of chromosomes
diploid
a cell containing 2 sets of chromosomes
polyploid
a cell that contains more than 2 sets of chromosomes
asexual reproduction
the production of offspring from a single parent cell by division (genetically identical) (mitosis)
3 stages of the cell cycle
interphase
mitosis
cytokinesis
gametes are ___ cells
haploid
fertilization
the fusion of a sperm and an egg to form a diploid fertilized egg (zygote)
meiosis
the process of making gametes in sexually reproducing organisms
3 main steps to meiosis
interphase
meiosis 1
meiosis 11 (2)
interphase (meiosis)
the DNA replicates and the cell prepares for meiosis
this occurs in a spermatocyte or oocyte which are both DIPLOID cells
homologous chromosomes
pair of chromosomes similar in shape and size
what is a tetrad
a pair of homologous chromosomes
meiosis 1: prophase 1
homologous chromosomes pair up beside each other (SYNAPSIS)
genetic information is exchanged (CROSSING OVER)
nuclear membrane disappears and spindle fibres form
crossing over
during prophase 1, synapsis occurs which forms a tetrad, and chromosome segments are exchanged within that tetrad
meiosis 1: metaphase 1
The homologous chromosomes line up in the middle in random assortment
meiosis 1: anaphase 1
the spindle fibers pull the homologous chromosomes to opposite poles
meiosis 1: telophase 1
the chromosomes reach the poles, spindle fibers dissolve, two new nuclei form
