Chapter 4 & 5 Flashcards
What is sex?
Gender?
- male/female
- person’s biological/anatomical sexual identity
- person’s socially defined sexual identity
What is an example of a species where the environment determines the sex of their offspring?
many reptiles
- turtles
Define genic?
alleles at autosomal loci
Which chromosome has female-promoting genes?
X
What has male promoting genes?
autosomes
Does the Y chromosome determine the sex of an offspring?
No
What is the use of the Y chromosome?
fertility in males
What determines the sex of an offspring?
the ratio of chromosomes to autosomes
What is the ratio of sex chromosomes (female) and autosomes (male)?
Female
- 1
Male
- 0.5
If the sex chromosomes to autosome ratio is between 1 and 0.5, what is this called?
intersex
What is the significane of the SRY gene?
any human with the SRY gene will be male
How does the SRY gene indicate a male offspring?
- some gonad tissue produces male sex hormones
- gonads develop into testes
- hormones suppress the female duct and produce other male characteristics
For females are both X chromosomes active?
no, only one
Females:
What is it called when only on X chromosome is active?
Barr body
What syndrom is diagnosed with X0 chromosomes?
What are the symptoms?
- Turner’s syndrome
- sterile femal
- some unnormal traits
What syndrom is diagnosed with XXY (XXXY, XXXXY, XXYY) chromosomes?
What are the symptoms?
- Kleinfelter’s syndrome
- sterile male
- likely without full male development
What syndrom is diagnosed with XXX (XXXX, XXXXX) chromosomes?
What are the symptoms?
- Triplo-X syndrome
- females may be sterile
- show little physical deviation from normal
- more X’s, more severe
What syndrom is diagnosed with XYY chromosomes?
What are the symptoms?
normal
What is the diagnosis of an intersex individual?
androgen insensitivity syndrome
Why could females never have the SRY gene?
SRY gene could be harmful to female
Where is the pseudo-autosomal regions located?
at the ends of the Y chromosome
What sex linkage?
a locus is on one sex chromosomes, not the other
What are the advantages of studying with fruit flies?
- short generations
- many offspring
- small
- only 4 pairs of chromosomes (8 total)
How did Morgan’s experiment with fruit flies support the chromosomal theory of inheritance?
- sex was determined by sex chromosomes
- genes must be on chromosomes
- eye color locus is on the X chromosome, not the Y chromosome
What is a reciprocal cross?
cross the parents, then reverse the sexes
- switch the genes from the mother to the father (vic versa), the cross
What is complete dominance?
when phenotypes of the heterozygote and dominant homozygote are identical
What ratio does Mendel’s traits cause?
3:1
Why is there complete dominance?
the recessive allele’s function is negated
Can complete dominance be qualitative, quantitative, or both?
only qualitative
What are a couple diseases caused by recessive alleles?
- cystic fibrosis
- Cl-transport protein
What can increase the speed of enzymes?
- build up of substrate
- a lower amount of product
What is incomplete dominance?
when one allele is not completely dominant over the other
What ratio dose incomplete dominance have?
Genotype?
Phenotype?
1:2:1
What is codominance?
when both alleles contribute to the phenotype
What is polydactyly?
extra fingers or toes
What is penetrance?
% of individuals having a certain genotype that express an expected phenotype
What is expressivity?
the degree to which a trait is expressed
What are lethal alleles?
alleles that cause the death of the organism that carries them
What is the phenotype ratio of lethal alleles?
2:1
What is Huntington’s disease in humans?
causes nerve cells (neurons) in parts of the brain to gradually break down and die
What is a gene interation?
a single phenotype is determined by more than one locus
What is an interaction with epistasis?
one epistatic locus masks or hides the effect of a second hypostatic locus
What is epistatic?
interaction of genes at different loci
What is hypostatic?
A gene that is affected by another gene
What is recessive epistasis?
What is its ratio?
- homozygous recessive condition at a locus that prevents the expression of phenotypes determined by a second locus
- 9:3:4
What is dominant epistasis?
What is the ratio?
- dominant genotype on one gene inhibits expression of another gene
- 12:3:1
What is duplicative recessive epistasis?
What is its ratio?
- homozygous recessive at either of two loci
- 9:7
What is complementation?
two parents with similar recessive phenotypes, whom produce offspring with a wild-type phenotype.
What are sex-influenced characteristics?
- traits that are controlled by genes on autosomes
- are expressed differently in males and females
What are sex-limited characteristics?
autosomal genes whose expression is limited to one sex
What is cytoplasmic inheritance?
transmission of genetic material independent of the nucleus
What are some distinct characteristics of the mitochondria and chloroplast?
- small chromosomes
- few genes
- materially inherited in most species
Multiple copies of chromosomes allow cells and individuals to be what?
chimeric (chimera)
What is epigenetics?
the study of environmental influences on gene expression that occur without a DNA change
What is DNA methylation?
What can it do?
- the addition of methyl groups to certain bases in DNA
- inhibit or completely turn off a gene
define a histone?
any of a group of basic proteins found in chromatin.
What is trans-generational epigenetics?
When parents transmit epigenetic changes in gene expression to their children.
What is anticipation?
when highly unstable repeated sequences increase in number very rapidly
What is the effect of anticipation?
mutations are fast enough to be visible within a single family
What are environmental effects?
anything other than genetics
What are continuous traits?
What are they called?
- require measurements for description
- quantitative characteristics
What is polygenic?
A trait that is controlled by many genes
What are multifactorial characteristics?
Characteristics influenced both by environmental and genetic factors.
What is pleiotrophy?
When one gene affects other genes it is not related to
