Chapter 2 Flashcards
Genes
Specific sequence of nucleotides and are recipes for making proteins
Normal human cells contain _____ chromosomes
46
Normal human cells contain _____ pairs of chromosomes
23
Mitosis
The cell’s nucleus making an exact copy of all the chromosomes and splitting into two new cells
Meiosis
The gamete’s chromosomes duplicate, and then divide twice resulting in four cells containing only half the genetic material of the original gamete
Genotype
Refers to the sum total of all the genes a person inherits
Phenotype
Refers to the features that are actually expressed
Homozygous
Receive either the same version of a gene from our mother and father
Heterozygous
If we receive a different version of the gene from each parent
Dominant Gene
Genes that express themselves in the phenotype
even when paired with a different version of the gene
Recessive Gene
Genes that express themselves only when paired with a similar version gene
Alleles
Different versions of a gene
Polygenic Genes
The result of several genes
Incomplete Dominance
The dominant gene does not completely suppress the recessive gene
Carriers
Those who have inherited only one recessive-gene
Monozygotic/Identical Twins
Identical twins occur when a fertilized egg splits apart in the first two weeks of development
Dizygotic/Fraternal Twins
Two eggs or ova are released and fertilized by two separate sperm
Sex-linked Genetic Disorders
The defective gene is found on the X-chromosome
Who is at greater risk for sex-linked genetic disorders: men or women?
Men
Recessive/Homozygous Disorders
- The individual inherits a gene change from both
parents - If the gene is inherited from just one parent, the person is a carrier and does not have the condition
Autosomal Dominant (Heterozygous) Disorders
In order to have the disorder, the individual only needs to inherit the gene change from one parent
Chromosomal Abnormality
Occurs when a child inherits too many or two few chromosomes
Trisomy 21/Down Syndrome
Occurs when there are three rather than two 21st chromosomes
What is the most common cause of chromosomal abnormalities?
The age of the mother
Sex-linked Chromosomal Abnormality
When the abnormality is on 23rd pair
Autosomal Chromosome Disorders
The individual inherits too many or two few
chromosomes
Genetic Counseling
A service that assists individuals identify, test for, and explain potential genetic conditions that could adversely affect themselves or their offspring
Behavioral Genetics
The scientific study of the interplay between the genetic and environmental contributions to behavior
Genotype-Environment Correlation
Refer to the processes by which genetic factors contribute to variations in the environment
Passive Genotype-Environment Correlation
Occurs when children passively inherit the genes and the environments their family provides
Evocative Genotype-Environment Correlation
Refers to how the social environment reacts to
individuals based on their inherited characteristics
Active Genotype-Environment Correlation
Occurs when individuals seek out environments that support their genetic tendencies
