3. Genetics Flashcards
3.1 What is a gene?
A sequence of DNA nucleotides that codes for heritable characteristics
3.1 What is a gene loci?
Where a gene is located on a chromosome
3.1 What is an allele?
A version of a gene
Alleles are located at the same locus with a slightly different sequence of nucleotides
3.1 Types of substiution mutations
Silent, Nonsense, Missense
3.1 What is the relevance of the COX gene?
a gene for cellular respiration that is present in most Euk. organism, allows for easy comparison of sequences
3.1 What is the cause of sickle cell amenia?
A substiution in the gene to make hemoglobin
3.1 Steps of Sickle Cell Anemia
The irregular hemoglobin causes the blood cell to bcecome a sickle shape which gets stuck in blood vessels –> anemia = not enough healthy cells to deliver o2
3.2 Describe Prokaryotic DNA
Known as the nucleoid, prokaryotic DNA is not enclosed, is a single naked loop
3.2 What is a nucleus
The Eukaryotic’s membrane bound organelle containing DNA
3.2 What is a nucleolus?
Structure in the nucleus responsible for ribosome production and assembly
3.2 What is a nucleosome?
Small lengthes of DNA wrapped around 8 histone protiens (building blocks of chromatins)
3.2 What is Chromatin
Loose form of DNA (chromosome material) not supercoiled, durng interphase
Chromosome = yarn ball
Chromatin = yarn string
3.2 What is a chromosome?
The supercoiled form of chromatin
3.2 What is a chromatid?
One side of a copied chromosome (arms of the same length)
3.2 Diploid vs Haploid
Diploid: Cell containg two complete sets of chromosomes, one from each parent
Haploid: One copy of each chromosome (sp, egg)
3.2 Heterosomes vs Autosomes
Autosomes - normal
Heterosomes - determine sex (x vs Y)
3.2 Homologous chromosomes
Share same structure, same genes at loci position (alleles can be different
- seperated
One comes from maternal, one from paternal
3.2 Chromosomes in Species
Organisms with different #s of chromosomes can’t interbreed
3.2 What causes species to have different #s of chromosomes?
- Splitting
- Fusing
- Evolution
3.2 What is a karyogram?
A micro-photograph of all the chromosomes for an individual
3.3 Whats the difference between Meiosis 1+2
M1: Diploid to haploid, 2 products, crossing over, procceded by DNA replication
M2: Haploid to haploid, 4 products, chromatids seperate, no crossing
3.3 DNA through meiosis
G1: single, non-super coiled DNA
S: 2 pairs of sister chromatids, homologous chromosomes
Prophase 1: DNA supercoils
Metaphase 1: Homo chromos at equator, crossing over
Anaphase 1: Seperate
Telophase 1: At poles, still with sister
Prophase 2: Supercoil again
Metaphase 2: Equator, not paired
Anaphase 2: Seperate
Telophase 2: Decondenses
3.3 Does crossing over happen in Mitosis or Meiosis?
Meiosis
3.3 What happens during prophase 1, meosis?
1) Pairing of homo chromos through synapsis : homochoromos attach at chiasmata (attachment sites) to form bivalent
2) Homo chromoes exchange pieces of non-sister chromatids @ chiasmata
3.3 Formula for possible chromosome combinations -
2^n (n is the number of chromosomes in haploid)
3.3 What is nondisjunction?
Failure of homo chromos to seperate, result = abnormal numbers
3.3 Draw the Process of Meiosis
3.3 Describe Two Methods of Fetal Cell Karotyping
1) Aminiocentesis- amnotic fluid is collected via needle in abdomen
2) Chronic Virus Sample - thin tube inserted for sample of placenta
3.3 What promotes genetic variation in Meiosis?
Crossing over and random orientation
3.4 What is Mendel’s Experiemtn
Through selectively breeding pea plants learned
1) Genes passed to offspring
2) One gene per parent
3) Recessive genes
3.4 Types of Allele Combinations (Dominancy)
1) Dominant/Recessive
2) Codominant
3) Sex-Linked
3.4 What allele type is sickle cell anemia
Codominant, red blood cell disease
3.4 What allele type is Red-Green Color Blindness?
Recessive, sex linked
3.4 What type of allele is Hemophillia?
recessive, sex-linked (X)
3.4 What type of allele is Cystic Fibrosis
recessive
3.4 What type of allele is Huntington’s?
Dominant
3.4 What are gametes?
Haploid cells with one allele of each gene, fuse together to create zygote
3.5 Descibe the process of gel electrophoresis
DNA samples are put in sample wells at the end of gel. These DNA samples are cut smaller, and naturally have a negative charge. Molecules move towards the positive electrode on the other end based on size with smaller molecules going farther (since they go faster). This creates a band to help identify.
3.5 What is the purpose of PCR?
Polymerase Chain Reaction is used to make many copies of DNA
3.5 What are the steps of PCR?
1) Denaturation
2) Annealing (cooling, primer binds)
3) Extension (Raise temperature to trigger TAQ polymerase)
3.5 What are the steps of DNA Profiling?
1) Sample of fluid collected
2) Reference sample collected
3) PCR used to make multiple copies
4) DNA is cut into fragements using restriction endonucleases
5) Electrophoresis
6) Bands are compared
3.5 What is cloning and how?
A clone is asexually produced via:
- Binary Fission
- Budding (cells splitting off)
- Fragementation (Seperated fragement)
- Parthenogenesis (unfertilized egg)
- Splitting of embryo
3.5 Describe Gene Transfer using Bacteria (for insulin)
- mRna is extracted from human pancreatic cells and using rever transcriptatse it becomes complementary DNA
- Plasmid is obtained from bacteria and cut with restrictive enzume
- Plasmid and cDNA fused together using DNA ligase
- Reintroduced to host cell
3.5 What is the process of Somatic Cell Cloning?
The nucleus from the somatic cell with desired genes is removed and placed in egg cell with its own nucleus thats been removed (nucleus replacement)
3.5 What are the pros and cons of GMO crops?
Pros:
- less insecticides
- Longer shelf life
- Increased nutrients
- More resistant
Cons:
-protiens could be toxic
-antibiotic resistant plasmids could spread
-contamination
- biodiversity risk
