Genetics/Meiosis Flashcards
what happens before mitosis
Interphase- cell grows replicates its chromosomes and gerts ready for cell division
what happens before meiosis occurs
Interphase- the DNA in each chromosome is replicated
what is the purpose of meiosis
to create sex cells
what is the purpose of mitosis
create more cells; growth repair
what does meiosis produce
four haploid cells in which each chromosome has just one chromatid.
what does mitosis produce
two daughter cells
What are Homologous chromosomes?
Two chromosomes in a pair normally one inherited from the mother and one from the father
What is the difference between a haploid cell and a diploid cell?
Diploid cells are two full sets of chromosomes while haploid cells are one full set of chromosomes.
What is the difference between autosomes and sex chromosomes?
Autosomes- 1-22
Sex- 23, XY determines gender
What identifies a human genetically as female? As male?
females inherit an X chromosome from the father for a XX genotype, while males inherit a Y chromosome from the father for a XY genotype (mothers only pass on X chromosomes)
What is a Karyotype?
an individual’s complete set of chromosomes.
What is nondisjunction?
When chromosomes don’t separate- its a mistake
what is crossing over
the process by which genetic material is exchanged/transfered by homologous chromosomes during meiosis- prophase I
How does crossing over occur
during meiosis when chromosomes of the same type are lined up
what is independent assortment
the alleles of two (or more) different genes get sorted into gametes independently of one another
How does independent assortment occur
when paired homologous are separated into daughter cells during meiosis.
How does independent assortment occur contribute to genetic diversity?
because certain genes are not connected with one another. some traits that are inherited from the parents will not clump together for the new offspring.
What is random fertilization
during sexual reproduction, the male gamete and female gamete that fuse to produce an offspring are selected randomly from the pool of male and female gametes.
how does random fertilization lead to genetic variation
When a male gamete and a female gamete finally meet, each is the result of an immense number of genetic possibilities created during independent assortment and crossing over.
what are the pedigree symbols for male and female
A male is represented by a square or the symbol ♂, a female by a circle or the symbol ♀.
what are the differences between genotype and phenotype
The phenotype is an organism’s physical appearance, and the genotype is the genetic makeup.
Genotype and Phenotype example
Genotype- Bb, Phenotype- brown fur
differences between an allele and a gene?
Gene is defined as a section of DNA that encodes for a certain trait.
An allele is defined as a variant form of a gene
differences between a Homozygous and Heterozygous?
Being homozygous for a particular gene means you inherited two identical versions. It’s the opposite of a heterozygous genotype, where the alleles are different.
Homozygous and Heterozygous example
Homozygous- BB bb, Heterozygous- Bb
Incomplete Dominance
a form of Gene interaction in which both alleles of a gene at a locus are partially expressed, often resulting in an intermediate or different phenotype
Codominance
means you see both of the traits such as having a cow with black spots means it has white and black genes,
Multiple Alleles
three or more possible alleles for one individual trait.
Sex Linkage
refers to characteristics (or traits) that are influenced by genes carried on the sex chromosomes.
What makes a trait sex-linked?
Refers to characteristics (or traits) that are influenced by genes carried on the sex chromosomes.
Sex-linked traits are determined by genes found on the X and Y chromosomes
Sex linkage applies to genes that are located on the sex chromosome
Are X linked recessive traits more common in men or women? Why?
X-linked recessive diseases most often occur in males. Males have only one X chromosome. A single recessive gene on that X chromosome will cause the disease
What are ways of determining whether a trait is dominant or recessive in a pedigree
if a trait skips a generation in a pedigree, it is often an autosomal recessive trait
What are ways of determining whether a trait is X-linked or autosome
Autosomal dominant traits pass from one parent onto their child
X linked traits are passed through mutations (changes) in a gene on the X chromosome
