lecture 8 Flashcards
What is non disjunction and where does it occur?
When too many chromosomes are being pulled on one end of the cells and none on the other side of the cells. This problem becomes noticeable in the anaphase.
Non disjunction can happen in meiosis II. Hapolid cells that have odd number of chromosomes can result from non disjunction.
What happens when meiosis goes wrong?
Meiosis makes mistakes. When meiosis makes mistakes it can have big consequences on the gametes.
What can non disjunction do in spermatogenesis?
In spermatogenesis it can give odd number of chromosomes.
How many homologous pairs of chromosomes do humans have?
Humans have 23 homologous pairs of chromosomes. Autosomes are numbered from largest to the smallest 1-22.
What can result in down syndrome?
Having 3 of chromosome 21 can result in down syndrome. Trisomy 21
What is independent assortment?
Heterozygote at two loci can produce four different combinations of alleles that are equally likely that is called independent assortment.
Dependent assortment
Predicts that the inheritance of physical characteristics are linked during gamete formation. The combinations that happen are not equally likely.
Why does linkage happens?
Linkage happens because of crossing over. Crossing over has generated new combinations. Some genotypes will be more common than others
Independent assortment
Independent all combinations are equally as likely
Linkage
not all combinations are as likely
Where does crossing over happens?
Crossing over happens in the same chromosomes
Example of non mendelian inheritance
Prokaryote with asexual reproduction
Bacteria are haploid, they go through binary fission and make a clone
Plasmid
Plasmid extra loop of dna , the cells bump into each other a dna go through a phase of conjugation, they connect the plasma together, inherited
Euglena
is diploid and it clones itself from the original cell.
What can reproduce asexually?
Multicellular eukaryotes can reproduce asexually as well.
how do some haploid eukaryote reproduce?
There are haploid eukaryote organisms that reproduce sexually.
What are some definitions for DNA?
Deoxyribo Nucleic Acid, the genetic materials of all known cells. Sugar-phosphate backbone with nucleic acid bases. A Polymer of nucleotides, each with a sugar, phosphate and nucleic acid base.
What parts are attached to each other in DNA?
The sugar and the phosphate are attached to each other
What are the nucleic bases?
Nucleic acid bases are Thymine, Adenine, Cytosine, Guanine
What do the nucleic acid bases form? what are they specific about?
The nucleic acid bases may from hydrogen bonds with each other because of their shape and their chemical processes. The Bases are very specific about which base they will form hydrogen bonds with.
Adenine goes with
Thymine
Guanine goes with
Cytosine
What is a base pair?
Two nucleic acid bases that are held together by hydrogen bonds are called a base pair.
How is DNA usually found?
DNA is typically found double stranded, with complementary strands held together by base pairs. The sequence on one base pairs complements the other base pair.
What must happen with DNA for cell division?
DNA must be replicated for cell division.
Enzyme
An enzyme is a protein that makes a chemical reaction take place more easily (acts as a catalyst)
Shape and orientation of DNA
Double stranded DNA is anti-parallele its important because it constrains interactions with the DNA. DNA polymerase is constrained to go in a certain directions, some proteins pull the DNA apart. (Dont need to know this) Need to know there are consequences to the antiparallele DNA cell.
Gene expression
is the process by which they influence the phenotype
What does DNA control?
Dna controls the production of certain protein and then the proteins influence the traits
DNA → Protein—> Trait Occurs more or less constantly in living cells
Examples of DNA → Protein—> Trait
Examples
ATAC—> iNSULIN
GCCT→ enzyme → Chlorophyl
How are certain genes expressed? Give examples
Some genes are only expressed by certain cells. Some genes are only expressed at certain times. Example: ears being formed, alleles being expressed only at that time.
What does RNA stand for?
RNA (Ribo Nucleic Acid)
DNA and RNA
DNA and RNA are similar
Both can be describe as a polymer…
They have a different sugar in RNA
RNA IS single stranded and DNA is double stranded
Differences in DNA and RNA
One of the four bases is different for RNA, Thymene is never found in RNA and ONLY IN DNA you find Uracil instead.
What are the three functions of RNA in the cell?
Messenger RNA (mRNA) carries a protein blueprint from DNA to ribosomes.
Transfer RNA (tRNA) Carries aminoacids to ribosomes
Ribosomal (rRna) With certain proteins, makes up ribosomes.
