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Human Genetics > Background for Human Genetics > Flashcards

Background for Human Genetics Flashcards

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Biology 101 flashcards
1
Q

What were Mendel’s laws? What did Mendel use to analyze inheritance?

A

Mendel’s Laws;
Law of dominance, law of Segregation and Law of independent assortment
He used GARDEN PEAS to analyze inheritance (grew peas, with different height and made them pure-bred (offspring identical to parent) and bred them again to observe traits inherited

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2
Q

Describe the advantages of peas?

A

Advantages of peas-
- Traits must be Simple and Distinct (peas had differing characteristics )
-controlled crosses must be EASY(protect hybrid of plants)
-Inbred lines and hybrids should be Healthy

peas were easy and fast to grow, and self-pollinate, short life cycle

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3
Q

Discuss an example of Mendelian trait seen in his experiment

A

Mendalian trait: plants have a copy of each allele of gene,
At a single genetic locus:
1 allele- for white flowers; another allele for Purple flowers
-Purple is dominant

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4
Q

Describe what occurs in Mendel’s law of Dominance and evidence of this

A

Dominance:
A dominant allele determines the phenotype when HETEROZYGOUS with a recessive allele
Purple allele- DOMINANT to white allele
example: cross purple (PP) with white (pp)
experiments with plants provide evidence that:
-Hybrids are NOT exactly the intermediate between the parental species ,
-in each of the 7 crosses, the hybrid character resembles that of one of Parental forms.

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5
Q

Explain what happens in Mendel’s Law of segregation. What does this mean?

A

Segregation:
each plant has 2 copies of a gene, which segregate from each other when forming gametes. Thus each gamete carries ONE copy of each gene
if you have at least two copies of a gene= HETEROZYGOUS
-if heterozygous genotype (Pp x Pp) you will have 3:1 phenotypic ratio (3 purple, 1 white)

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6
Q

Explain them Mendel’s law of Independent Assortment

A

Independent Assortment: the alleles of two Different genes assort independently into gametes
-mendel used peas for this experiment and if you cross two plants with different alleles, they will have different traits
(ex: RY, Ry, ry, rY x RY, Ry, ry, rY will create 16 combinations for genotype and 9:3:3:1 phenotype ratio)

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7
Q

What are Mendel’s true breeding traits ? What are some examples?

A

Mendel’s true breeding traits- describes plants that self-pollinate and produce offspring with the same traits
The organism is HOMOZYGOUS for every trait and have identical alleles for specific traits (offspring will have same phenotype as parent)
ex of true-breeding traits: round or wrinkled seeds, purple or white petals, long or short stems, axial or terminal flowers

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8
Q

what is the role of the nucleus in the cell?

A

Nucleus- is the center of the cell and carries genetic information. This Information is presented in form of chromosomes In the nucleus

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9
Q

How does Mitosis contribute to importance of DNA?

A

Mitosis- multi-step process that will duplicate chromosomes, including DNA that it contains, hence mitosis suggests there is genetic info on chromosomes
mitosis ensures that each cellular generate will have SAME genetic compostion (DNA) as previous generation

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10
Q

Describe the people and experiments involved in discovering that DNA carries the genetic information in the nucleus

A

DNA carries the genetic information in the nucleus:
-Johann Friedrich Mischer discovers “nuclein in the nuclei of white blood cells (1874) (first to isolate nucleic acid)
-Albrecht Kossel shows that nuclein contains Deoxyribonucleic Acid (DNA) and identifies its four BASES(1878)
-Oswald Avery, Colin MacLeod and Maclyn McCarty show that DNA , NOT proteins carries genetic information from one bacterium to another (1943) using rats and 2 bacterial strains

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11
Q

Explain what occurred in Avery, Macleod and McCarty Experiment and its significance for genetics

A

Avery, Macleod and McCarty Experiment:
- 2 bacterial strains that included 1 rough strain (non-virulent ) and 1 Smooth strain (virulent)
-one test was injected mice with Rough strain and mice survives
-second test injected mice with smooth strain (virulent) and mice dies
-third test injected mice with heat treated S-strain which kept mice alive
-fourth test injected mice with a mix of heat-treated S and R which causes mice to die.
When they used DNASE (enzyme chew up DNA) and heat-treated S + R strain, mouse was ALIVE
when protease used (enzyme to chew up proteins) and heat-treated S + R strain, mouse dies.
This proved that DNA must be genetic material or transformable material within cell.

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12
Q

What is the importance of X-ray crystallography in genetics? How was it used?

A

X-ray crystallography was used to determine 3D structure of a molecule
-by making crystals of a molecule (crystals in ordered array), use X-ray to shine light o crystal and discover structure of proteins or macromolecules.
-way of finding information for DNA STRUCTURE

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13
Q

Who was Rosalind Franklin and what did she discover? Who were Watson and Crick?

A

Rosalind Franklin used X-ray crystallography to discover DNA structure as a HELIX.
Watson and Crick used Rosalind’s discovery of DNA image (helix) to create their own model of DNA as double helix (two-strand).

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14
Q

Explain the context of We have found the secret of life

A

We have found the secret of life; is a quote said by Watson and Crick who sat a pub and discovered DNA as 3D double helix structure. They also mentioned that DNA was life’s hereditary material; DNA holds and passes down genetic information that will be passed from parent to offspring.

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15
Q

Describe the structure of DNA and how it is connected

A

DNA is a double helix composed of 4 types of bases (adenine, cytosine, thymine and guanine)
Watson and Crick discovered the 4 bases and that they are held together by HYDROGEN BONDS (weak interactions)

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16
Q

Explain how the bases in DNA interact and why they are important
Which bases pairs with each other and which base pair is stronger? Also what forms the DNA Zipper and why is this important?

A

The 4 bases of DNA interact through hydrogen bonds.
Oxygen or nitrogen atoms are slightly negative and hydrogen atoms are slightly positive
-Adenine pairs with Thymine
-Cytosine pairs with Guanine
The G-C bond is STRONGEST
Hydrogen bonds form the DNA zipper and due to weak interactions of H-bond. DNA can unwind and pull strands apart

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17
Q

How can the structure of DNA influence genetics?

A

The STRUCTURE of DNA can explain the laws of genetics through processes of DNA Replication, RNA processing, and RNA Translation
its structure describes the way generic information can be passed down to offspring

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18
Q

Explain the importance of DNA structure and process of DNA replication

A

DNA replication is the process of making two identical copies of DNA from the original DNA strand.
Process:
Each DNA strand is the TEMPLATE for a new DNA molecule .
As DNA strands are pulled apart by helper proteins (helices), DNA polymerase will synthesize new single strands on each side; forming 2 copies identical to original .
humans create replication bubbles at replication origins allowing DNA strand to open and for new strands to be made on each single strand. When all strands meet and connect, 2 daughter helices are formed.

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19
Q

What occurs in DNA Transcription and how it influences molecular basis of genetics

A

DNA Transcription:
RNA is synthesized from DNA
-first you have DNA strand
Then RNA polymerase binds to another strand and make copies
ribosomal DNA is important in process of making proteins (does NOT make protein)
*process of transcription:
-DNA is unwound
-RNA POLYMERASE binds the ANTISENSE Strand (template strand for making mRNA)
-RNA Polymerase matches RNA nucleotides to DNA pairs
-in RNA, U matches A , but in DNA, T matches A
(new RNA sequences are complimentary to the DNA template from which they were made)

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20
Q

What is role of transcription factors in DNA transcription?

A

Transcription factors control when each gene is expressed.
These factors will bind to DNA strand and cause RNA copies to be made or prevent RNA copies from being made.

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21
Q

What is the role of Regulatory proteins in transcription?

A

Regulatory proteins control WHERE RNA polymerase binds
both activator and enhancer proteins all influence regions of DNA molecule that DNA polymerase will make RNA transcript

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22
Q

Which is more stable RNA or DNA? WHY?

A

DNA is MORE stable, as it makes better, long term genetic material
DNA has one less oxygen-containing hydroxyl group in its deoxyribose sugar, allowing it to be able to keep genetic info safe
-RNA is Less stable than DNA (RNA uses Uracil)
RNA is single stranded and has ribose sugar that is very reactive and contains two OH groups.

23
Q

Explain how human RNAs must be processed? What regulates translation?

A

Human RNAs must be processed:
1. A protective cap is added to 5’ end of RNA (at its beginning)
2. A string of A’s is added to the 3’ end of RNA
-Poly A tails vary in length
-Poly A tails regulate Translation.
3. Introns are REMOVED by splicing to make a long open reading frame.
4. ligase the exons together to have mature mRNA transcript
(shorter RNA)

24
Q

what is the role of mature RNA transcripts/

A

Mature RNA transcripts carry information out of the nucleus.
-this info is later used to make proteins(during translation)

25
Q

what are the roles of proteins?

A

proteins: make food, build material, structural component (give cell shape) and has enzymatic functions (chemical reactions)

26
Q

Explain what occurs during RNA Translation, including the process

A

RNA Translation: process of making a protein from information contained in messenger RNA or mRNA
-translate RNA to proteins using tRNA molecules.
Process:
1. ribosomes read an mRNA, starting at the 5’ end
2. tRNA’s deliver amino acids to the ribosome
3. The correct amino acids are selected by base-pairing between each mRNA codon and tRNA anticodon.
-tRNA- are the keys to translate genetic code to protein

27
Q

How many nucleotides are needed to make 1 amino acid? Which codon are used for Start and stop

A

Each set of THREE Nucleotides is needed ro make an amino acid.
The FIRST codon is always: AUG= Methionine–> START codon
The LAST codon is always UAA, UAG, or UGA which are STOP codons

28
Q

Discuss the role of tRNA and its structure.
What is the role of the Aminoacyl tRNA synthase?

A

tRNAs (transfer RNA) carry amino acids to ribosomes.
-Each tRNA has an anticodon that binds to three nucleotides of the DNA coding region
-The tRNA also has an attachment site at its 3’ end that carries an amino
-Aminoacyl tRNA synthases connect the proper amino acid to each tRNA
tRNA structure: R-shaped molecule, with anticodon loop and 4 helices (loops) and attachment site where amino acids are attached.

29
Q

where is the insulin gene located?

A

Insulin gene located in genomic DNA from CHROMOSOME 11

30
Q

explain the process of how insulin gene is made into a protein

A

process:
-the insulin gene is in genomic DNA chromosome 11.
1. RNA polymerase makes a primary transcript
2. RNA is capped at the 5’ end, cleaved at the 3’ end and A POLYADENYLATED
3. Splicing factors then bind sequences at the edges of each intron (as each introns are removed, exons spliced together)
4. The introns are removed and the mature transcript is exported from the nucleus.
5. A ribosome then translates the message into prepoinsulin (starting with start codon AUG and ending with STOP codon UAG) Each triplet (codon) will be translated to an amino acid
6. prepoinsulin is then passed through the membrane and cleaved (process of translation, translocation, folding and cleavage, packaging, etc) to create final mature insulin

31
Q

What are the splice donor and splice acceptor signals?

A

Splice donor signal: GU at 5’ end of intron
splice acceptor: CAG (at 3’ end)
all these signals are places where introns will be removed.

32
Q

Explain the process of prepoinsulin becoming mature insulin

A

process:
1. translation and translocation (pass through membrane )
2. folding, oxidation and signal peptide cleavage
3. ER export, Golgi transport, vesicle packaging
4. Protease cleavage liberates C-peptide
5. carboxypeptidase E produces mature insulin

33
Q

Describe the structure of a chromosome and what it includes

A

Structure of a chromosome contains:
DNA (Double helix form) wrapped around proteins called HISTONES.
These Histones help to give the chromosome stability.
since, DNA is THIN and LONG, you need proteins like histones to protect it.

34
Q

differentiate between chromatin and nucleosome

A

chromatin-DNA wrapped around histones
Nucleosome- repeating subunit of chromatin packaged inside cell’s nucleus

35
Q

what are different ways of measuring genetic variation ?

A

Gel electrophoresis and Southern blots

36
Q

Which method is used to view differences in proteins and how?

A

GEL ELECTROPHORESIS allows us to view differences in PROTEINS
-used to separate proteins based on Size and Charge (applying an electric current through a gel and watching molecule migrate or move towards its opposite charge)

sanger (1st to sequence Proteins)

37
Q

which method allows us to view differences in whole DNA samples?

A

SOUTHERN BLOTS allow us to view differences in whole DNA samples.
process:
- extracting DNA from blood sample and digest it (enzyme)
-using gel electrophoresis to separate DNA fragments by size
- transfer fragments onto nylon membrane (blotting sheet)
- use radioactive probe to hybridize only to coplkementary sequence
-expose to x-ray and probe will label specific fragment

38
Q

What is the role of the PCR (polymerase chain reaction)? what is used for this process?

A

The polymerase chain reaction (PCR)- AMPLIFIES Specific DNA Sequences
-this reaction uses Normal process of DNA replication

39
Q

what kind of DNA polymerase is used in PCR?

A

DNA polymerase comes from a species that lives in hot springs, so it can survive hot temperatures
-This polymerase is called Taq polymerase
-specific DNA primers bind the template and initiate replication in the right place.

40
Q

what is the process of PCR?

A

The process of PCR:
1. DENATURATION ( boil at 95 degrees C, to separate the DNA strands).
2. ANNEALING: (cool to 50-62 degrees C, so primers can bind the DNA
-precise temperature depends on the primers
3. EXTENSION: heat up to 72 degrees to allow replication of the template (temp depends on enzyme)
4. PCR machine repeats these steps for 35 cycles
5.. The Desired DNA increases exponentially

41
Q

Describe the main stages of PCR

A

stages in PCR:
-initial cycles produce products to AMPLIFY
-Later cycles exponentially INCREASE the amount of product

42
Q

Which methods help identify SNPS (single nucleotide polymorphisms?

A

PCR and Sequencing are used to identify SNPs
SNPS represents a difference in single DNA building block (or region)
process:
-amplify a small region of DNA using an appropriate pair of primers
-sequence this DNA region from each individual
-SNPS will have a VARIABLE sequence

43
Q

what kind of genomes do humans have?

A

DIVERSE GENOMES (SNP density increases along 22 chromosomes)

44
Q

where does the greatest genetic diversity exist? What happens to genetic diversity during migrations ?

A

AFRICA (greatest genetic diversity)
Genetic diversity DECREASES during successive and early migrations
-the further away we get from Africa, the LOWER the amount of genetic diversity

45
Q

what happened to genetic diversity during successive migrations?

A

During successive migrations, genetic diversity decreases
after a series of bottleneck migrations, a change from diverse source to less diverse community occurs (ex: migration from Africa to Europe, Asia and americas and Australia

46
Q

what is Central Dogma?

A

Central Dogma describes the transfer of genetic material from DNA to RNA to protein.

47
Q

how many copies of a gene do people have ?

A

people have TWO copies of each gene

48
Q

why is structure of DNA important?

A

Structure of DNA explains the ability of genes to replicate, store and use information

49
Q

What is a missense mutation?

A

Missense mutation: A single nucleotide change that alters the genetic codon and produces a DIFFERENT AMINO ACID than the original amino acid.

Ex: if GAA (code for Glutamate) changed to GAC, it would become a codon for Aspartate (another amino acid)

50
Q

What is a frame shift mutation?

A

Frameshift mutation: caused by insertion or deletion of a nucleotide that will cause number of base pairs that are Not a multiple of three and SHIFTS the Reading Frame of DNA sequence
(lead to a different protein)

51
Q

What is a nonsense mutation?

A

Nonsense mutation: a mutation that results in changing an amino acid and producing a STOP codon (terminating translation; creating non-functional protein)
ex: change from ATC to UAC (stop codon)

52
Q

What is a silent mutation?

A

Silent mutation: a mutation that causes change in nucleotide, however does not change the amino acid in sequence or affect functionality (simply change codon; same amino acid is present)
ex: change in nucleotide from AAG to AAA will still give same amino acid lysine (only 1 nucleotide changed)

53
Q

What is the product rule?

A

Product rule: if 2 events are indecent (don’t influence each other), the probability of both events occurring is equal to P(event 1) x P (event 2)
ex; Does event 1 AND event 2 occur?

54
Q

What is the Addition Rule?

A

Addition Rule: (The probability of A or B )= P (A) + P (B) - P(AB).

Human Genetics (13 decks)

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