Biological information (genetics)

Question 1

Who are Watson & Crick + Rosalind Franklin

Answer 1

well technically Rosalind franklin, found and photographed the double helix in DNA (meaning that there are two strands

Question 2

What do chromosomes contain?

Answer 2

They contain DNA (genetic material)
- Each chromosome contains one long DNA molecule with hundreds or thousands of genes

Question 3

What is each chain of DNA made up of?

Answer 3

each chain is made up of four kinds of chemical building blocks called nucleotides and abbreviated as A, G, C, and T

Question 4

What is a ‘medelian’ disease?

Answer 4

a genetic disease in humans that is due to a mutation in a single gene

Question 5

How many pairs of chromosomes do humans have?

Answer 5

humans have 23 pairs of chromosomes (46 in total)

Question 6

What is gene expression?

Answer 6

it is the process of converting information gene to cellular product

Question 7

What is autosomal dominant?

Answer 7

on average 50% of the children are affected with the disease and 50% are unaffected

Question 8

What is autosomal recessive?

Answer 8

On average 25% of children are normal, 50% are carriers and 25% are affected with the disease

Question 9

What does it mean to be an x-linked trait?

Answer 9

• All female from an affected male will be carriers of the disease
• On average 50% of male children from a female carrier will have the disease and 50% of female children will be carriers

Question 10

What is an example of an autosomal dominant disease?

Answer 10

Huntington’s disease

Question 11

Example of autosomal recessive diseases:

Answer 11

• cystic fibrosis
• Sickle cell anemia

Question 12

Example of x-linked recessive diseases:

Answer 12

Hemophilia A

Question 13

How many single disorders are there?

Answer 13

over 7,000

Question 14

What did Mendel study?

Answer 14

He studied, flower color, flower position, seed color, seed texture, pod texture, pod color and plant height

Question 15

Why was Mendel so successful?

Answer 15

1. he investigated the inheritance of only one or two traits at a time
2. He kept accurate quantitative data

Question 16

What is a dominant cross?

Answer 16

offspring show ne parents phenotype only

Question 17

What is a recessive cross?

Answer 17

reappearance of the second phenotype

Question 18

What is the difference between phenotype and genotype?

Answer 18

Phenotype - physical appearance
Genotype - genetic makeup

Question 19

What is the law of segregation?

Answer 19

the two alleles for a heritable character segregate (separate from each other) during gamete formation and end up in different gametes

Question 20

What is Mendel’s second law?

Answer 20

This is the law of independent assortment, each trait is inherited independently of the other

Question 21

What is the ratio of combined probabilities ( green x yellow, wrinkled x smooth)

Answer 21

The ratio is 9:3:3:1 you multiply after the punnet square

Question 22

What are the degrees of dominance?

Answer 22

1. Complete dominance: occurs when phenotypes of the heterozygote and dominant homozygote are identical
2. Incomplete dominance: the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties
3. codominance: two dominant alleles affect the phenotype in separate, distinguishable ways

Question 23

What is pleiotropy?

Answer 23

• multiple phenotype effects
  -Obvious for syndromic diseases where a mutation in one gene can cause defects in multiple tissues.

Question 24

Def mitosis:

Answer 24

cell division involving somatic cells

Question 25

Def meiosis:

Answer 25

cell division involving gametes (egg and sperm cells)

Question 26

How much of the cell cycle is interphase?

Answer 26

About 90% of the cell cycle is in interphase, this is when DNA in the nucleus is replicated (interphase consists of the G1, S, and G2 phase

Question 27

Draw the process of mitosis and meiosis:

Question 28

What is a diploid cell?

Answer 28

one pair of of homologous chromosomes

Question 29

When a diploid cell replicates what is it known as?

Answer 29

two sister chromatids

Question 30

In meiosis 1 what happens?

Answer 30

each cell receives only one of the homologues

Question 31

In meiosis 2 what happens?

Answer 31

Each cell only receives one sister chromatid (these are haploid cells)

Question 32

What does crossing over do?

Answer 32

it shuffles genetic material during the process of gamete formation

Question 33

In a monohybrid cross what is the ratio?

Answer 33

3:1 (dominant: recessive)

Question 34

What are the rules about linkage?

Answer 34

1. genes located on different chromosomes are NOT linked (allowing independent assortment)
2. genes that are located very close together on the same chromosome may show complete linkage, they may also be so close the can’t be separated during during crossing-over
3. Genes located far apart on the same chromosome typically show incomplete or partial linkage because they are easily separated

Question 35

What is it called when offspring match with one of the parental types?

Answer 35

phenotypes that match a parent are called parental types

Question 36

what happens when two genes are far apart?

Answer 36

1. higher probability that a cross-over will occur between them
2. the higher the recombination frequency
   - This is because the greater the distance between two genes the more points there are between them, where crossing over can occur

Question 37

What was Griffith’s experiment?

Answer 37

to inject mice with the different strain types and observe the effect on mice and analyze their blood for bacteria

Question 38

What is horizontal gene transfer?

Answer 38

the movement of genetic material between unicellular and or multicellular organisms

Question 39

What are the steps of horizontal gene transfer?

Answer 39

Transformation: involves uptake of short fragments of naked DNA by naturally transformable bacteria
Transduction: involves the transfer transfer of DNA from one bacterium into another via bacteriophage
Conjugation: involves transfer of DNA via sexual pilus and requires cell-to-cell contact

Question 40

What did the Hershey-Chase experiment prove?

Answer 40

Protein was not genetic material but DNA was

Question 41

What does a chromosome consist of?

Answer 41

DNA molecule and tightly packed proteins

Question 42

What does it mean when chromatin is packed tightly?

Answer 42

This means that it is harder for genes to express their genetic information, which means that if they are loose it is easier to express genetic information

Question 43

What are epigenetics?

Answer 43

heritable changes in gene expression (active vs. inactive genes) that are not due to changes to the DNA sequence

Question 44

What are steps to DNA replication?

Answer 44

There is one continuous strand which is the “conservative strand” and the other is put in in chunks RNA primer (5’ to 3’) and these are called okazaki fragments

Question 45

DNA replication and there proteins:

Answer 45

Helicase: unwind the strand
Single stranded binding protein: binds to and stabilizes single-stranded DNA until it is used as a template
Topoisomerase: relieves unwinding strain, rejoins DNA strand
primase: Synthesizes at 5’ end of leading strand okazaki fragment

Question 46

What is messenger RNA?

Answer 46

also known as mRNA
- transcribed from ‘protein-coding’ genes
encode the information for specific proteins.
- low abundance

Question 47

Ribosomal RNA:

Answer 47

rRNA
- structural and functional component of ribosomes
- the most abundant RNA in a cell
-rRNA is very stable
-rRNA os a non-coding RNA