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Genetics Flashcards

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Biology 101 flashcards
1
Q

All living things contain:

A

Deoxyribonucleic acid (DNA)

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2
Q

Humans have how many chromosomes?

A

46 chromosomes, 23 from each parent

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3
Q

What is a chromosome?

A

Package of DNA with part or all the genetic material of an organism

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4
Q

What is special about sperm and egg cells?

A

They have 23 chromosomes because they are haploid. Through fertilization they join and make a cell with 46 chromosomes.

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5
Q

What is a somatic cell?

A

Any of the body cells except the reproductive (germ) cells. Has 46 chromosomes.

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6
Q

How many pairs of chromosomes are there?

A
  • 22 pairs (autosomes) that contain important genes
  • 1 pair (sex chromosomes) that have fewer genes and influence gender
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7
Q

What are genes and what do they do?

A

They are organized sections of DNA that:
- code for protein
- aid in the maintenance of cells
- control a particular trait

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8
Q

What are alleles?

A

Different variations of genes that control traits. Everyone has two alleles for a trait, one from each parent.

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9
Q

What is mitosis?

A

Type of cell division for somatic cells and for asexual reproduction. It produces two identical daughter cells and it’s important because it ensures genetic continuity within an organism for growth, repair and development.

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10
Q

The Cell Cycle

A
  1. Interphase: the cell is not dividing
  2. Mitosis
    i. Prophase: chromosomes coil up
    ii. Metaphase: chromosomes lineup in center
    iii. Anaphase: chromosome separate to opposite poles
    iv. Telophase: chromosomes and coil and cleavage furrows
  3. Cytokinesis: two daughters cells are created, each with its own nucleus and identical chromosomes
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11
Q

What is meiosis

A

Cell division for the production of gametes and sexual reproduction. Two cell divisions, creating four gametes with haploid number of chromosomes. Meiosis II is exactly the same as mitosis, it just happens to two cells at the same time.

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12
Q

What is gametogenesis?

A

The production of gametes through meiosis

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13
Q

What is spermatogenesis?

A

Meiosis and nails, which occurs in the testes. Starts with a diploid cell called us spermatogonium it produces four identical haploid sperm cells meiosis produces 250,000 sperm every day in males.

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14
Q

What is oogenesis?

A

Meiosis and females which occurs in the ovaries and oviducts. Starts with a diploid cell called an oogonium. Production starts before a female is born, but causes in Meiosis I before the cells divide. After Telophase I and II, one of the cells receives a majority of the cytoplasm, resulting in one egg cell and three polar bodies. This unequal division allows the egg cell to have sufficient nutrients to support a zygote immediately after fertilization.

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15
Q

What are congenital defects?

A

Clinical health problems visible at birth. There are caused by mutations in genes or environmental agents.

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16
Q

What is meiotic non-disjunction?

A

When the chromosomes lineup in myosis in ways other than the usual pairings (ex. The chromosomes don’t split)

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17
Q

What is down syndrome?

A

A chromosomal genetic disorder where people have an extra chromosome 21

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18
Q

What will happen if the mutated chromosome is copied?

A

These chromosomes are copied during interphase. All daughter cells will carry the mutation if that sperm or egg is a part of fertilization. The new organism will carry that error and all of its cells.

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19
Q

What is non-disjunction?

A

The failure of chromosomes or tetrads to separate during anaphase this result in the addition of deletion of a chromosome in a gamete

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20
Q

What is trisomy?

A

A gamete with an extra chromosome is fertilized by a normal gamete, and the zygote has an extra chromosome

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21
Q

What is monosomy?

A

Gamete missing a chromosome is fertilized by a normal gamete and the zygote will have only one copy of a chromosome

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22
Q

What is trisomy 21?

A

A person has three copies of chromosome 21 instead of two. Results in Down Syndrome
This causes:
- mental delay
- weaker cardiovascular system
- widely spaced eyes
- receding forehead
-protruding tongue

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23
Q

What is Klinefelter’s Syndrome?

A

Individual is XXY. Non-disjunction error in anaphase. Infertile males, varying degrees of femininity.

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24
Q

What is Turner syndrome?

A

Individual only gets one sex chromosome: an x. This causes:
- infertile female
-broad chest
-poor breast development
- short stature
- poor hearing

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25
Q

How are DNA tests done?

A
  1. Isolate and replicate DNA
  2. Cut the DNA with restriction enzymes (each enzyme looks for a specific pattern)
  3. Place fragmented DNA in the wells of a polyacrylamide gel and electrophoresis is performed
  4. DNA (-) is attracted to the bottom (+)
    • smaller fragments of DNA move quicker than larger pieces
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26
Q

What did Frederic Miescher do?

A

Discovered DNA when he isolated a substance from the place of cell that he called “nuclein”. His student called it nucleic acid.

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27
Q

What are the two types of nucleic acid?

A

DNA and RNA

28
Q

What did Frederick Griffith do?

A

He heated pneumonia and injected it into mice immediately. He discovered that cells can convert from a harmless form to a disease causing type.

29
Q

What did Erwin Chargaff discover?

A

He discovered that there are always equal amounts of Adenine and Thymine, and equal amounts of Cytosine and Guanine. He proposed that they bond together in some way

30
Q

Who discovered the helical structure of DNA?

A

Rosalind Franklin took pictures of it in an xray. She had her work stolen by James Watson, Francis Crick and Maurice Wilkins, who received a Nobel prize for their discovery.

31
Q

What are the sugars in DNA and RNA?

A

DNA: deoxyribose
RNA: Ribose

32
Q

What are the two nucleotides in DNA and RNA?

A

Purines and Pyridimines

33
Q

What are purines?

A

Two-Carbon nitrogen ring bases

34
Q

What are pyridimines?

A

One-Carbon nitrogen ring bases

35
Q

What is the difference between the appearance of DNA and RNA?

A

DNA has two strands that form a double helix, while RNA has one

36
Q

What is a polymer?

A

A repeated unit of nucleotides

37
Q

Why are the nitrogenous bases of DNA attracted to each other?

A

The basis attract each other because of hydrogen bonds hydrogen bonds are weak, but there are millions within a molecule of DNA. How many hydrogen bonds do and thymine cause. A+T= 2 HB, C+G=3 HB

38
Q

Each DNA cell has about __m of DNA

A

2

39
Q

The average human has __ trillion cells

A

75

40
Q

5 types of chromosomal mutations:

A
  1. Deletion: loss of DNA segment
  2. Duplication: extra copies of DNA segment
  3. Inversion: segment breaks off and reattaches in reverse orientation
  4. Translocation: chromosome beaks the whole or a portion and reattaches to other chromosome
  5. Non-disjunction: failure to separate during anaphase, abnormal daughter cell
41
Q

What is a gene mutation?

A

Any change to the DNA sequence of a gene. Small scale if it only affects one gene. Nucleotides/bases may be added, missing or moved. 2 types.

42
Q

What are the two types of gene mutations?

A
  1. Point Mutation
    - one base (A,T,C, or G) is substituted for another
    - causes sickle cell anemia
    - 3 possible consequences:
    *nonsense mutations- code for a stop, which can translate the protein
    *missense mutations- code for a different amino acid
    *silent mutations- code for the same amino acid
  2. Frameshift mutation
    - one or more bases (A,T,C, or G) are added or deleted
    - causes cystic fibrosis
    - caused by:
    *insertion- adding a base
    *deletion- removing a base
43
Q

What causes a mutation?

A
  • physical conditions (ex. radiation, extreme heat)
  • chemical conditions (molecules that misplace base pairs or disrupt the helical shape of DNA)

These would all have to occur during DNA replication to force a mutation

44
Q

Why are mutated proteins dangerous?

A

A mutated gene will make a mutated protein. Mutant proteins do not go where they’re supposed to go or do what they are supposed to do.

45
Q

How many genes do humans have?

A

25 000, over 50% of genome is repeating sentences

46
Q

What is humans genetic variation like?

A

Very little genetic variation, 99.9% of humans are the same

47
Q

What did Gregor Mendel do?

A

He used pea plants to study genetics, heredity, and variation.

48
Q

What did Anton Van Leeuwenhoek do?

A

He discovered sperm and designed the first microscope. He believed that he saw a complete miniature person in the head of a sperm (homunculi)

49
Q

What did the 19th century British believe in?

A

They believe in a blending theory of inheritance. This is the theory that offspring have a blend or mix of the characteristics of their parents. Mendel noticed plants in his own garden did not follow this theory.

50
Q

What did Charles Darwin do?

A

He theorize that offsprings have variations of their parents characteristics, but was unable to explain why

51
Q

If you breed a tall and dwarf plant, why might all of their offsprings be tall?

A

Heights could be a dominant trait which outweighs the recessive trait of being a dwarf

52
Q

What is a phenotype?

A

The appearance of traits in an organism

53
Q

What is a genotype?

A

The specific genes that an organism has (which alleles, dominant or recessive)

54
Q

What are Mendel’s laws and principles?

A

Law of segregation: when any individual produces gametes, the copies of a gene separate so that each gamete receives only one copy of a gene, and therefore only one allele for all possible traits

Law of independent assortment: alleles of different genes assort independently of one another during gamete formation, so different traits are inherited independently of each other. If you are able to be dominant for one trait, it will have no influence and whether you will be dominant for another trait.

55
Q

What does incomplete masking?

A

Neither trait is dominant or recessive. A heterozygous individual is a blend of these two traits

56
Q

What is codominance?

A

Oh wheels for a trait or dominant, a heterozygous individual expresses both equally

57
Q

What is sickle cell anemia?

A

It’s an inherited condition that results in a decrease in the ability of red blood cells to carry oxygen throughout the body. Causes:

  • resistance to malaria
  • hard irregularly shaped blood cells (like a crescent moon)
  • pain
  • damage to organs
  • death
58
Q

What are the three alleles of blood?

A

A, B, and O

59
Q

What are the four types of blood?

A
  1. Type A: IaIa or Iai
  2. Type B: IbIb or Ibi
  3. Type AB: IbIa
  4. Type O: ii
60
Q

What is polygenic inheritance?

A

The inheritance of a trait governed find more than one gene

61
Q

What did Thomas Morgan do?

A

Studied eyecolor, using fruit flies as test subjects. Red eyes were dominant over white eyes, and he was unable to produce a female with white eyes. He concluded that the gene must be located on the chromosome and that it is sex linked.

62
Q

What are some examples of sex linked disorders?

A
  • red green colour deficiency (CVD)
  • hemophilia
  • x-linked severe combined immunodeficiency
63
Q

What is hemophilia?

A

It affects the bodies ability to produce proteins involved in blood clotting and is x-linked recessive. It causes internal bleeding.

64
Q

What are Barr bodies?

A

Every cell in a female has one functioning X chromosome. A shrivelled chromosome is called a Barr body.

65
Q

What is autosomal dominant inheritance?

A

Single copy of an allele that is sufficient to cause expression of a trait. It is not on sex chromosomes.

66
Q

What is autosomal recessive inheritance?

A

Two recessive alleles result in a trait being expressed

  1. May not have affected parents, parents would have to be carriers though
  2. Affects both sexes equally, can skip generations
  3. Two affected parents will have affected children (100% chance)
67
Q

What are microarrays?

A

A lab tool used to detect the expression of thousands of jeans at the same time.

Grey: not present
Yellow: in both cells
Green: in normal cells
Red: in disease cells

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