WK1 Chapter 2 Learning Outcomes Flashcards
Distinguish between genotype and phenotype and identify
the different forms of genetic inheritance.
There are 46 chromosomes in the human genome, organised into
23 pairs. The totality of an individual’s genes is the genotype, and
the person’s actual characteristics are ca led the phenotype.
Genotype and phenotype may be different, due to dominant
recessive inheritance, incomplete dominance and environmental
influences. Most human characteristics are polygenic
Describe the sex chromosomes and identify what makes
them different from other chromosomes.
The sex chromosomes determine whether the person wil be male
or female. In the female this pair is caled XX; in the male, XY.
Having only one X chromosome makes males more vulnerable than
females to a variety of recessive disorders that are linked to the X
chromosome.
Explain how behaviour geneticists use heritability
estimates and concordance rates in their research.
Heritability estimates indicate the degree to which a characteristic
is believed to be influenced by genes within a specific population.
Concordance rates indicate the degree of similarity between
people with different amounts of their genes in common; for
example, MZ and DZ twins.
Describe how the concept of epigenesis frames gene
environment interactions and connect epigenesis to the concept of
reaction range.
Epigenesis is the concept that development results from
bidirectional interactions between genotype and environment. The
concept of reaction range also involves gene–environment
interactions because it means that genes set a range for
development and environment determines where development fals
within that range.
Explain how the theory of genotype → environment effects
casts new light on the old nature–nurture debate.
Rather than viewing nature and nurture as separate forces, this
theory proposes that genes influence environments through three
types of genotype → environment effects: passive, evocative and
active. The three types of effects operate throughout the life span
but their relative balance changes with time
Outline the process of meiosis in the formation of
reproductive ce ls and specify how the process differs for males
and females.
In meiosis, cels that begin with 23 pairs of chromosomes split and
replicate repeatedly until they form four gametes, each with 23
individual chromosomes. In males, the outcome of meiosis is four
viable sperm, but in females, meiosis produces only one viable
ovum. Also, males produce milions of sperm daily beginning in
puberty, whereas females produce al the eggs they wil ever have
while sti l in their mother’s womb
Describe the process of fertilisation and conception.
About 14 days into a woman’s menstrual cycle, an ovum is
released into the falopian tube. When fertilisation occurs, the 23
chromosomes from the ovum pair up with the 23 chromosomes
from the sperm and a new cel, the zygote, is formed from the two
gametes. The zygote’s 46 paired chromosomes constitute the new
organism’s unique genotype, set once and for al at the moment of
conception
About 14 days into a woman’s menstrual cycle, an ovum is
released into the falopian tube. When fertilisation occurs, the 23
chromosomes from the ovum pair up with the 23 chromosomes
from the sperm and a new cel, the zygote, is formed from the two
gametes. The zygote’s 46 paired chromosomes constitute the new
organism’s unique genotype, set once and for al at the moment of
conception
Explain how chromosomal disorders occur.
Chromosomal disorders occur when the chromosomes fail to divide
properly during meiosis. These disorders may involve the sex
chromosomes or may take place on the 21st pair of chromosomes,
resulting in a condition known as Down syndrome. Risks of
chromosomal disorders rise with parental age
Describe the main techniques of prenatal diagnosis and
explain who is likely to seek genetic counse ling and for what
purposes.
Prenatal diagnosis may include ultrasound, amniocentesis and
chorionic vi lus sampling (CVS), and non-invasive prenatal testing.
Couples who may be at high risk for genetic disorders sometimes
seek genetic counse ling prior to attempting pregnancy
List the major causes of infertility for both men and
women and describe current treatments.
Male infertility may be caused by too few sperm, poor quality of
sperm or low motility of sperm. Female infertility is most often
caused by problems in ovulation. Infertility in both men and women
is often due to age, but it can also be genetic or caused by
behaviour such as drug abuse, alcohol abuse or cigarette smoking.
Treatments for infertility are termed assisted reproductive
technologies (ART) and include artificial insemination, fertility drugs
and IVF.
Compare rates of fertility worldwide and contrast views
of infertility in developed and developing countries.
Although worldwide the average infertility rate is about 10–15%,
there is variation among countries. In developed countries, infertility
often results in frustration and sadness, and presents a chalenge
to the couple’s relationship, although it may ultimately make the
relationship stronger
