Chapter 4 - Genetics

Front 1

Genetic material is composed of

Back 1

DNA (deoxyribonucleic acid), which is a very long molecule, twisted into a double helix like a spiral staircase, with a sugar-phosphate backbone and four types of nitrogenous bases (the steps of a staircase)

Front 2

DNA is composed of

Back 2

a sugar-phosphate backbone and four types of nitrogenous bases

Front 3

The four bases of DNA are

Back 3

Adenine double bonded to thymine
Guanine triple bonded to cytosine

Front 4

Thymine pairs with

Back 4

adenine

Front 5

Cytosine pairs with

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guanine

Front 6

Adenine pairs with

Back 6

thymine

Front 7

Guanine pairs with

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cytosine

Front 8

How many bonds connects Adenine to Thymine

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two bonds

Front 9

How many bonds connect Guanine to Cytosine

Back 9

three bonds

Front 10

RNA uses uracil instead of

Back 10

thymine

Front 11

So in RNA adenine binds with

Back 11

uracil

Front 12

The DNA is present in the nucleus in separate strands known as

Back 12

chromosomes

Front 13

How many pairs of chromosomes are in the human

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23 - one comes from the individuals mother and one comes from the individuals father

Front 14

Each chromosome is made up of a long sequence of

Back 14

A,T, G, and C bases

Front 15

Sequences of these bases that code for a trait are called

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genes

Front 16

Each chromosome contains

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hundreds of genes that are made up of sequences of Adenine, Thymine, Guanine and Cytosine bases

Front 17

What directs protein synthesis

Back 17

sequences on genes

Front 18

Three bases in a row is called a

Back 18

codon, and it codes for a particular amino acid

Front 19

Gene

Back 19

sequence of DNA (sequences of bases that code for a trait)

Front 20

Transcription

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is when RNA makes a copy of the DNA in the nucleus. It then passes outside the nucleus through small pores in the nuclear membrane

Front 21

Translation

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is when ribosomes "read" the RNA (like someone reading a book in Braille) and selects an amino acid that corresponds to the codon. The amino acids are then attached together to form a peptide, and larger peptides form proteins.

Front 22

What forms a peptide

Back 22

amino acids attached together

Front 23

Larger peptides

Back 23

form proteins

Front 24

Proteins are made up of

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amino acids

Front 25

Mutations

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can occur in the DNA sequence, which will cause it to be read incorrectly. This causes a defective or non-functional protein to be formed.

Front 26

Meiosis

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The process by which the cells divides its genetic material in half to create two gametes

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Gametes

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in the human female are eggs, in the male are sperm

Front 28

How many chromosomes are numbered

Back 28

22

Front 29

22 pairs of chromosomes are numbered

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from largest to smallest and are called autosomes

Front 30

Autosomes

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are 22 pairs of numbered chromosomes

Front 31

What are the other pair of chromosomes other than the autosomes

Back 31

the sex chromosomes X & Y

Front 32

What determines the sex of the person

Back 32

the X & Y chromosomes

Front 33

XX

Back 33

Female

Front 34

XY

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Male

Front 35

What are the sex-linked genes

Back 35

Genes on the X & Y chromosomes

Front 36

Kleinfelter syndrome

Back 36

is a defect in meiosis that results in XXY

Front 37

Turner syndrome

Back 37

XO

Front 38

Karyotype

Back 38

is an ordered display display of chromosomes. They are photographed during mitosis, cut apart and arranged with the matching pairs together

Front 39

Aneuploidy

Back 39

having an unusual amount of chromosomes

Front 40

Trisomy

Back 40

having three copies of a particular chromosome

Front 41

Down Syndrome

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Trisomy 21

Front 42

Autosomal trisomies of chromosome 13 and 18

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can result in live births, but the infants can often only survive for a few days.

Front 43

Autosomal trisomies

Back 43

most often result in miscarriage

Front 44

Which autosomal trisomies can survive

Back 44

8 and 16

Front 45

Trisomy mosaics

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(where some of the cells carry 3 copies of an autosomal chromosome and some cells have 2) have a better chance of survival

Front 46

What is the only monosomy that can survive?

Back 46

XO - Turner's syndrome

Front 47

Which autosomal monosomy cannot survive?

Back 47

one of the numbered chromosomes - YO - and will result in miscarriage

Front 48

Trisomy results from

Back 48

a process called nondisjunction, where the chromosome pairs do not separate into the two daughter cells during meiosis

Front 49

Nondisjunction

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where the chromosome pairs do not separate into the two daughter cells during meiosis

Front 50

Nondisjunction is more likely to occur

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the older a women gets

Front 51

Amniocentesis

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takes a sample of amniotic fluid so that cells can be grown and the dividing cells can be photographed to create a karyotype to check for chromosome abnormalities

Front 52

Genetic problems occur

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when chromosomes are altered

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Deletion

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is when a piece of a chromosome is missing (example is Cri du Chat syndrome

Front 54

Cri du Chat syndrome

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occurs from deletion and a piece of a chromosome is missing

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Duplication

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is when a segment of DNA in a chromosome is repeated. It may cause mental retardation.

Front 56

Inversion

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is when a sequence is inverted. The individual may not be affected, but its offspring often are.

Front 57

Translocations

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are where part of the chromosome is stuck on another. In the case where chromosome 21 is stuck to another chromosome, it can cause Down syndrome or miscarriage

Front 58

What are the main causes of miscarriages and mental retardation

Back 58

chromosomal abnormalities including trisomies and altered chromosomes

Front 59

Dominant defective genes

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cause a problem when only one defective gene copy is present

Front 60

Recessive defective genes

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requires a defective gene to be inherited by both parents

Front 61

Carriers

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individuals that have one normal gene and one defective gene

Front 62

If two individuals who are carriers of a recessive gene mutation have a child, what are the chances that the child will inherit the defective gene from each parent

Back 62

25%

Front 63

What is used to see the pattern of inheritance of a particular disease?

Back 63

Pedigree charts and Punnett squares

Front 64

Huntington's Disease

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autosomal dominant - but does not show up until after age of 40 - often when the affected person has already had children

Front 65

Cystic fibrosis

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autosomal recessive

Front 66

Genetic tests

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are available to screen prospective parents to see if they are carriers of Cystic Fibrosis or Tay Sach's disease or any other abnormal genes

Front 67

Genotype

Back 67

is the genetic makeup - what is present in the genes

Front 68

Phenotype

Back 68

is the way the genes are expressed. Recessive genes (blue eyes) can be hidden by dominant genes (brown eyes) - XY individuals with a mutated gene for testosterone expression will appear externally to be female (Androgen Insensitivity Syndrome)