Test 7: Genetics Flashcards
What is DNA?
DNA is the hereditary blueprint for all biological traits and processes. It is the original copy of a gene.
What structure is DNA?
Double helix structure.
What is chromatin?
It is the mass of DNA in a nondividing cell.
What happens when the cell divides?
Chromatin DNA contracts itself into compact “sticks” called chromosomes.
What is a karyotype?
It is the representation of a complete set of chromosomes.
How many chromosomes do humans have?
We have 46 chromosomes or 23 pairs of homologous chromosomes (one set from each parent).
What does DNA contain?
- Sugars, phosphate groups (sugar phosphate backbone)
- Nitrogen bases (A, T, G, C)
Where do we find DNA?
In the nucleus.
What is mRNA?
A duplicate copy of a gene.
Where do we find mRNA?
In the nucleus and cytoplasm.
What structure is mRNA?
Single strand structure.
What are the mRNA bases?
A-U G-C
Where do we find tRNA?
In the cytoplasm.
What are the tRNA bases?
A-U G-C, tRNA carried bases in triplets.
What structure is tRNA?
Clover shaped.
What is a gene?
It is a segment of DNA.
What do genes do?
- Provide the instructions for making proteins.
- Will code for a series of amino acids which will make a functional protein.
Why is the genetic code said to be a triplet code?
Because a series of 3 nitrogen bases comprised of some combination of A, T, G or C, will code for a particular amino acid.
What’s a genome?
It is a complete set of genes. The A-T-G-C sequence for all genetic information.
What do eukaryotic cells contain?
They contain a membrane bound nucleus which contains DNA.
How many proteins does the human body contain?
30 000 - 50 000
Give examples of specific roles proteins play in the body.
- Hormones
- Antibodies
- Enzymes
- Hemoglobin
What do proteins determine?
Proteins determine the character traits of an organism.
What are the building blocks of proteins?
Amino acids.
What is transcription and where does it occur?
- From DNA to mRNA
- Inside the nucleus
What are the steps during transcription?
- The double helix DNA unwinds
- A copy of a gene is made (random free bases pair up with the bases of DNA to copy)
- The mRNA can now leave the nucleus, into the cytoplasm
What is translation and where does it occur?
- From mRNA to protein
- On the ribosomes
What are the steps during translation?
- mRNA carries the instructions of the gene to the ribosomes
- The ribosome slides among the mRNA and reads each triplet
- Each triplet encodes for one different amino acid
- tRNA brings each amino acid to the corresponding mRNA triplet
- When the amino acids are linked, the RNA is released
(ribosome allows tRNA and mRNA to link, ribosome slides along mRNA and reads it in triplets, tRNA links and codes an amino acid)
What is folding?
The synthesized protein is released from the ribosome, folds into its functional shape and can now perform its role in the body.
What is heredity?
The transmission of characteristics from parent to offspring.
What are phenotypes?
Physical traits of the organism.
What is a genotype?
Type of alleles (2) for a specific gene.
What’s an allele?
A form of gene.
What’s a dominant allele?
It takes priority, it’s visible. (uppercase letter)
What’s a recessive trait?
It doesn’t take priority, it’s not visible. (lowercase letter)
What’s homozygous?
Two of the same alleles. (HH) (hh)
What is heterozygous?
Two different alleles. (Hh)
What’s crossbreeding?
The exchange of gametes between 2 different individuals during sexual reproduction.
What’s a monohybrid cross?
Cross with one trait.
What’s a dihybrid cross?
Cross with two traits.
What’s pure line?
Individuals who for a specific character trait only produce offspring with the same trait.
What’a a hybrid?
Individual obtained by crossbreeding 2 genetically different individuals.
What’s the Law of Segregation of Alleles?
Gametes carry only one allele for a gene.
What’s Mendel’s Law of Independent Assortment?
When gametes are formed, alleles are randomly assorted. (no link between alleles)
What’s a punnett square?
Technique for calculating the probability of different progeny.
