Inheritance and Traits Flashcards
What is dominant and what is recessive?
What does it mean to be a carrier
T or F : To have a recessive visible trait, you must have two copies of that gene. To have a dominant, you only need one dominant
True
there is no universal mechanism by which dominant and recessive alleles act. T or F
True. There is a lot of unpredictability about it and we are still learning.
T or F : dominant allele + dominant allele = dominant phenotype
dominant allele + recessive allele = dominant phenotype
recessive allele + recessive allele = recessive phenotype
This is correct. It’s true!
T or F. Dominant phenotypes are more common than recessive phenotypes
False. Not always. A population with a lot of light colored eyes for example is common in places like Scandinavia.
Dominant or Recessive genes are not better than the other. T or F
True. One is not better than the other.
What is a broken allele?
An allele that doesn’t work properly
The environment does not affect genetics, traits
F: height, tongue rolling, etc. can be affected by environment as well as hereditary traits.
Dimples are considered an “irregular” dominant trait
True
Freckles are controlled primarily by the MC1R gene.
True
What is an allele
Different forms of a gene, which produce variations in a genetically inherited trait. (Different alleles produce different hair colors—brown, blond, red, black, etc.)
What are genes?
Genes are parts of DNA and carry hereditary information passed from parents to children. Genes contain blue‐print for each individual for her or his specific traits.
What is dominant?
Dominant version (allele) of a gene shows its specific trait even if only one parent passed the gene to the child.When a child inherits dominant brown‐hair gene form (allele) from dad, the child will have brown hair.
What is recessive?
Recessive gene shows its specific trait when both parents pass the gene to the child.
When a child inherits recessive blue‐eye gene form (allele) from both mom and dad, the child will have blue eyes.
What is homozygous?
Two of the same form of a gene—one from mom and the other from dad.Inheriting the same blue eye gene form from both parents result in a homozygous gene
what are heterzygous?
Two different forms of a gene—one from mom and the other from dad are different.
What is a genotype?
Internal heredity information that contain genetic code.
What is a phenotype?
Outwardly expressed traits or characteristics. Both having or not having a widow’s peak are phenotypes
What is mendelian inheritance?
A simple genetic rule where a gene only comes in dominant or recessive forms. Some genetic traits follow Mendelian Inheritance, while other genetic traits follow different inheritance patterns or rules.
What is Sex-linked Mendelian Inheritance?
traits that are located on the autosomes but are influenced by the gender of the individual.
Differentiate between phenotype and genotype?
What are platelets?
fragments of cytoplasm which stops us from bleeding. hemophilia can affect this.
hemophilia is sex linked recessive disorder T or F
True.
What is a sex chromosome?
X or Y chromosome. It’s usually the last two.
T or F: Everyone has a Y chromosome
False. Everyone has an X chromosome.
There are genetic disorders where you can have extra copies of sex chromosomes. True or False.
True
Most sex like chromosomes are on the X chromosome.
True.
Colorblindness is also a sex lined recessive disorder.
True.
Why was the fruitfully significant to sex and classic genetics?
It showed the first demonstration for sex linked traits such as drosophila. mutations in the eye color made it white. this was a sex linked disorder and was linked to mating.
What is linkage?
“Linkage” refers to the physical connection that exists between genes whose loci are on the same chromosome. Genes on the X chromosome are all linked to each other—thus they are X-linked.
X-linked traits is that males always receive their X chromosomes from their mothers, so they also receive any X-linked traits from their mothers. Their fathers have no contribution for those genes (though, of course, they do for the genes on all of the other chromosomes). True or False?
True
X-linked recessive traits appear far more commonly in females than in males.
False. X-linked recessive traits appear far more commonly in males than in females.
There are no Y Linked disorders. T or F
False. There are a few genes which are Y-linked (or holandric). Y-linked genes are carried on the Y chromosome, and are thus passed directly from father to son. Every son has a copy of his father’s Y chromosome. In any pedigree showing unbroken lines of male descent, all of the connected males have copies of the same Y chromosome, and thus share any Y-linked characteristics.
FACT: Cryptorchidism is a genetically determined condition in which one or both testicles fail to make this voyage, and remain in the abdomen. (This is generally surgically corrected very early, because not only is a cryptorchid male sterile, but the undescended testicles are at increased risk for testicular cancer). The genes for this condition are autosomal; males and females each carry two alleles. But only males can possible exhibit the condition, because only males show the normal condition for testicle behavior and position.
Do you understand this?
Describe sex limited and sex influenced genes traits
These are autosomonal. They are not on the sex genes. they are expressed phenotypically.
Where are x linked genes found?
on the X chromosome
Where are y linked genes found?
on the Y chromosome
Where are sex limited and sex influenced traits found?
on autosomes (non sex chromosomes)
X linked facts
Hemophilia in humans is determined by a recessive X-linked allele.
An unaffected woman whose father has hemophilia man
marries a normal man.
Determine the probability of their child having hemophilia. What is the probability of a son having hemophilia?
What is the probability of a daughter having hemophilia?
Y linked facts
Never occur in females
Passed from father to all sons
Not dominant or recessive because of homozygosity
Facts about sex limited traits
Expression occurs only in one sex
100% expression in one sex and 0% expression in the other
Usually due to anatomical or hormonal differences between the sexes.
Facts about sex influenced traits
Expression is influenced by the sex of the individual
Hormones affect expression
The trait may be dominant in one sex and recessive in the opposite sex
Steps to solve crosses on punnet squares
Steps
* Write down symbols for the alleles
* Determine the genotypes of the parents
* Identify the gametes produced by the parents
* Make a Punnett square of the appropriate size
* Determine the genotypes of the offspring
* Determine the phenotypes of the offspring
* Answer the question depending on what is asked
Names some recessive genes
straight hair, attached earlobes, short eyelashes, red hair color, non-roller tongue, straight hairline, hitchhikers thumb, non PTC taster
Names some dominant genes
curly hair, free earlobes, long eyelashes, non-red hair color, roller tongue, widows peak hairline, straight thumb, PTC taster
