Ch. 3 Flashcards
(34 cards)
genes are …
specific sequence of nucleotides and are recipes for making proteins
proteins are responsible for …
influencing the structure and functions of cells
genes are located on … there are an estimated … genes for humans
the chromosomes, 20,500
mitosis is defined as …
the cell’s nucleus making an exact copy of all the chromosomes and splitting into two new cells
in meiosis the …
gamete’s chromosomes duplicate and then divide twice resulting in four cells containing only half the genetic material of the original gamete
normal human cells contain __ chromosomes in the …
46, nucleus of the cells
the word genotype refers to …
the sum total of all the genes a person inherits
the word phenotype refers to …
the features that are actually expressed
define homozygous
receiving either the same version of a gene from our mother and father
define heterozygous
receiving a different version of the gene from each parent
describe dominant genes
a gene that expresses themselves in the phenotype even when paired with a different version of the gene
describe recessive genes
a gene that expresses themselves only when when paired with a similar version gene
genetics refer to …
different versions of a gene as well as alleles
provide four examples of dominant traits
facial dimples, curly hair, normal vision and dark hair
provide three examples of recessive traits
red hair, being nearsighted, and straight hair
most characteristics are not the result of a single gene; they are ______, meaning …
polygenic, they are the result of several genes
describe incomplete dominance
the dominant gene does not completely suppress the recessive gene
most know genetic disorder are …; however, the vast majority of … are not …
dominant gene-linked; dominant gene linked disorders … serious of debilitating
recessive gene disorders are ____ common, but actually claim more lives because …
less, they are less likely to be detected as people are unaware that they are carriers of the disease
a chromosomal abnormality occurs when …
a child inherits too many or too few chromosomes
the most common cause of chromosomal abnormalities is … why?
the age of the mother. the ovum is more likely to suffer abnormalities due to longer term exposure to environmental factors
name one of the most common chromosomal abnormalities. when does it occur?
Trisomy 1 or Down syndrome.
occurs when there are three rather than two 21st chromosomes
when the abnormality is on the 23rd pair the result is a …
sex-linked chromosomal abnormality
two of the more common sex-linked chromosomal disorders are … and …
Turner syndrome and Klinefelter syndrome
