chapter 2 Flashcards
(29 cards)
what is DNA?
molecules that carry genetic instruction
what are genes?
segments of DNA that direct development
what are chromosomes?
structures in cells that hold genes
how many pairs of chromosomes are in each human cell?
23 pairs (with 46 chromosomes total)
how many chromosomes are in a sperm and egg cell?
they each have 23
what is mitosis?
cell division that creates identical body cells; important for growth
what is meiosis?
cell division that creates sperm and egg cells; important for reproduction
what is a genotype?
genetic blueprint of someone
what is a phenotype?
someone’s observable traits
what determines phenotype?
the interaction of genes and the enviornment
what is a chromosome?
tiny structures in the nucleus that contain genetic material
what is single gene inheritance?
the transmission of traits or conditions controlled by a single gene
what are alleles?
different forms of a gene
what does it mean to be homozygous?
to have same alleles
what does it mean to be heterozygous?
to have different alleles
what are dominant alleles?
they show an expressed trait
what are recessive alleles?
they are expressed only when paired together
what is incomplete dominance?
the blend of both alleles
what are sex-linked disorders?
they often affect males more
what is polygenic inheritance?
many genes contribute to a trait (like height or intelligence)
what is down syndrome?
caused by an extra 21st chromosome (often caused in meiosis); risk increases with maternal age
what does behavioral genetics do?
it examines how genes and the environment influence traits
what is heritability?
the statistical estimate of genetic influence
what is a shared environment
makes siblings similar
