Lab 6 Flashcards
Where are all of genes located
On chromosomes in the nucleus
Each chromosome contains what?
Long DNA strand bearing thousands of genes
Chromosome is made up of
Which is a combination of
Chromatin
DNA and protein molecules (histones)
The histomes help
Organize the chromatin and control expression of genes
DNA strands must be what? To do what
Rightly packaged to fit into cells
Chromatin exists as what do that the machinery can access different ?
Diffuse mass of fibers
Segments of DNA depending which genes need to be expressed or silenced
DNA is copied during
Replication and chromatin fibers coil up
Each chromosome consists of two identical
Sister chromatids original and copy
Karyotyoe
Break open cell and divide into pairs that match size and pattern
Homologous chromosomes Carey genes
Controlling same heritable traits
Alleles
Different versions of same gene
Homozygous heterozygous
Two identical alleles
Two different
Sperm and egg carries how many alleles and why
1
Because two homologous separated during meiosis
Haploid spent and haploid egg meet what is formed
Entirely unique combo of alleles (genotype) is expressed as phenotypes or traits in diploid individual
Identical twins develop
When early divisions of zygote produce two separate embryos that develop independently
Some phenotypic relationships are controlled by a single gene with two alleles that have a clear
Dominant recessive relationships
Heterozygous one allele determined individuals appearance and is called
The other has no noticeable effect
Dominant
Recessive
Freckles are a
Single gene trait
What is when some single gene traits the dominant recessive relationship is not clear
Incomplete dominance
The additive effects of two or more genes on a single phenotypic trait
Polygenic inheritance
Sex determination depends on
Composition of 23rd homologous pair
Females XX
Makes XY
Make sperm carries either an
X or Y
Sex linked genes
Those genes in sperm or egg unrelated to sec
X is larger than Y it
Therefore it is more likely than females to
Carries more sex linked genes
Express recessive sex linked traits
A single recessive allele will be expressed if appears on X and unopposed by matching portion of Y
Different disorders
Recessive
Dominant
Sex linked recessive alleles
Unique variations create a
DNA fingerprint
How is a DNA fingerprint made
DNA extracted from individuals cell cut into fragments at specific places with enzyme DNA
Cutting points
Vary and cut into unique set of DNA fragments that vary in number and length
How are cut fragments organized
Gel electrophoresis
Electric current
Repels negativel charged fragments
Which fragments travel faster
Shorter producing a ladder separated by size
Once gene identified as responsible for genetic disorder a specific enzyme used to
Generate fragments from the DNA of individuals that carry and express it
Carry it unexpressed
Those that don’t Carry
Compare DNA fingerprints to determine whether
Carry the gene
