Chapter 2L Single Gene inheritance

what is forward genetic?

A method that identifies the genetic basis of a phenotype using mutants or wildtypes and working backwards to find the responsible gene

how did gregor mendel demonstrate the existence of genes?

By using pure lines and crossing them together to examine the phenotypes of a hybrid

How did Mendel examine the offsprings of hybrids?

By performing selfed and carrying out testcross

Why are the principles that Mendel discovered universal?

As they reflect core mechanisms of meiosis

***What are pure lines?

they are homozygous organisms

What did Mendel study with to discover the existence of genes?

He use the common pea plant that were pure lines (aka homozygous organisms)

How did mendel study using pea plants that were pure lines?

He crossed them with each other, resulting the (F1) generation that only were yellow seeds

What is cross pollination?

A process where the pollen of one flower is transferred to another, breeding two different plants together to view the seeds that are produced

What is selfing?

A process where a plant performs self-pollination, passing on genes of a single parent

What did mendel do with the (F1) children?

He selfed the (F1) children, resulting in (F2) children that had both yellow and green seeds rather than yellow seeds only

Why did green seeds reappear in the F₂ generation along with yellow seeds?

Because the “green” trait was not lost in the original (P₀) parents—it was masked by the dominant “yellow” trait in the F₁ generation and reappeared in the F₂ generation

• showing the difference between dominant and recessive traits.

What did mendel conclude from his study using pea plants?

Even though the (F1) generation looked similar to the (P0) parents, they were genetically different

How did Mendel perform test cross on the pea plants?

He took the (F1) generation pea plants and crossed them with a pure line that exhibited the recessive “green” trait, resulting in a (F2) generation that had both yellow and green seeds

How are phenotypes determined?

By alleles from both parents that are passed down to the next generation with each parent giving one of their alleles

How did Mendel explain the results from his study on pea plants?

By using a punnett square as it showed the selfing of a pea plant resulted in a 3:1 ratio and the test cross of a pea plant resulting in a 1:1 ratio, pointing him to there being equal segregation of genes in gametes

What is monohybrid crosses?

A genetic cross between two organisms that are heterozygous for a single trait

What are genotypes?

The alleles that are responsible for the physical appearance of an organism

What are homozygous dominant individuals?

Individuals that have two identical copies of a dominant allele for a specific trait

What are heterozygous individuals?

Individuals that has two different alleles for a specific gene

What are homozygous recessive individuals?

Individuals that have two identical copies of a recessive allele for a specific trait

What are phenotypes?

They are physical traits that are expressed by an organism

Who discovered chromosomes?

Walther flemming in 1882

What does the metaphase ensure?

that genetic material are equally segregated and assorted independently

What does metaphase form?

they form a synapsis during meiosis

What are synapsis?

A pair of 2 chromosomes that are aligned with each other and exchange genetic material, resulting in a tetrad

What are sister chromatids segregated into during mitosis?

they are segregated into two diploid daughter cells that are genetically identical to the original parent cell

What are homologous chromosomes segregated into during meiosis?

they are segregated into two diploid daughter cells during the 1st division and are both further segregated into 4 haploid daughter cells during the 2nd division that are genetically different from each other and from the original parent cell due to recombination

What is the law of equal segregation?

Mendels first law that states two alleles at a gene locus can segregate from each other into gametes evenly, allowing for each gamete to have an equal probability to have either allele

Who Nettie Stevens?

One of the first scientists to find that sex is determined by a particular configuration of chromosomes

What is autosomal inheritance?

A type of inheritance involving the genes on the non-sex chromosomes being passed down to both male and female equally

What is Sex-linked inheritance?

A type of inheritance involving the genes on the sex chromosome being passed down and leading to different inheritance patterns in both male an female

What did Morgans experiment demonstrate?

It demonstrated that sex-linked inheritance existed based in the inheritance pattern seen on his fruit fly experiment

What is the autosomal recessive disorder?

A disorder that occurs when a child inherits two copies of a mutated gene from two normal parent, one from each parent, and is frequently shown to skip generations

What is the autosomal dominant disorder?

A disorder that occurs when a child inherits a mutated gene from parent and are able to transmit the trait

• Additionally, the disorder is rarely skipped and is the only inheritance that can possibly result in a non-affected daughter

What is the X-linked recessive disorder?

A disorder caused by a mutated gene on the X chromosome that mainly affects males, with females becoming carriers of the gene rather than being affected

• Additionally, carrier females have a 50/50 chance of passing on the gene to all their sons and will result in them becoming affected

• Furthermore, two unaffected parents have the chance to produce an affected son but NOT affected daughters

What is the X-linked dominant disorder?

A disorder caused by a mutated gene on the X chromosome that affects males and females similarly and are only transmitted from father to daughter, never from father to son

• With affected mothers passing on the trait to half their sons and daughters

What is Y-linked inheritance?

A type of inheritance that can only be passed down from father to son

What is Mitochondrial inheritance?

A type of inheritance that is passed down from a mother to their children

What is the Tay-Sachs disease?

A rare disorder passed on from parents to child caused by the malfunction of the hexosaminidase A enzyme, responsible for breaking down fatty substances, resulting in toxic levels rising in a childs brain and affecting nerve cell function