Genetics And Reproduction - Part One

Front 1

What are plasmids?

Back 1

-occur in bacteria
-small circular structures consisting of DNA
-can divide independent of cell division
- in general, their enzymes they encode for are involved with drug metabolism or the pumping of drugs out of the cell

Front 2

What is a possible way that antibiotic resistance occurs?

Back 2

plasmids can be shared by different stains of bacteria

Front 3

What is the basis for recombinant DNA technology?

Back 3

inserting genes coding for certain proteins into plasmids (or viral vectors)
substances such as insulin, erythropoietin, and growth hormone are generally generated in this manner.

Front 4

What is the chromosomes called in the resting state?

Back 4

chromatin or chromatin material
-very amprphous appearance
-DNA + chaparone basic protiens (called histones)

Front 5

What is a histones?

Back 5

any basic group of protiens found in chromatin

Front 6

What are the fxn of telomeres?

Back 6

- end of chromatin
- genome stability
-chromosomal pairing & seperation during cell division.

Front 7

What happens if the telomeres are damaged?

Back 7

- cell cycle arrest
- senscence (deteriation with age)
- apoptosis

Front 8

Cancer and telomere...

Back 8

if the telomere doesn't shorten then the cell can continue to divide and predisposes it to cancer.

Front 9

What is the composition of the double strands of DNA?

Back 9

nucleotides:purine and pyrimidine bases
deixyribose sugar, and phosphate
covalent bonds between ph and sugar

Front 10

How many have about how many genes?

Back 10

30,000- 50,000
3 x 109 bases

Front 11

The double strand happens partly as a result of the attraction between....

Back 11

adenine and thymine
cytosine and guanine

- weak bonds : H or Van der Waals force

Front 12

What is the significance of the weak bonds in DNA?

Back 12

Allows the strands to be seperated by heat and then cooled and recombined
This is IMPORTANT to PCR... polymersachain reaction = allows little strands of DNA to be duplicated and analyzed.

Front 13

What is taq polymerase?

Back 13

heat resistant, DNA polymerase

Front 14

What are the two types of strands of DNA?

Back 14

antisense
sense

Front 15

What is RNA called in genetic replication?

Back 15

DNA is transcribed into RNA, which becomes the template, or antisense strand

Front 16

Codon

Back 16

Three bases (sometimes referred to as a triplet) encode
for an amino acid

Front 17

How many chromosomes does each human have?

Back 17

46

Front 18

What is gene linkage?

Back 18

occurs when particular alleles are inherited jointly

Front 19

structural genes

Back 19

encode for structural protiens

Front 20

spacer segments

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Portions of DNA between coding segments

Front 21

regulatory genes

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a gene involved in controlling the expression of one or more other genes. A regulator gene may encode a protein, or it may work at the level of RNA

Front 22

introns

Back 22

-Noncoding (in terms of their failure to be transcribed into specific proteins) regions of
DNA exist between the coding segments or exons. These noncoding segments are
referred to as introns.

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alternative splicing

Back 23

Alternative splicing is the process that occurs in eukaryotes in which the splicing process of a pre-mRNA transcribed from one gene can lead to different mature mRNA molecules and therefore to different proteins

Front 24

alleles

Back 24

an allele (pronounced al-eel or al-e-ul) is any one of a number of viable DNA codings occupying a given locus (position) on a chromosome. Usually alleles are DNA (deoxyribo-nucleic acid) sequences that code for a gene, but sometimes the term is used to refer to a non-gene sequence. An individual's genotype for that gene is the set of alleles it happens to possess. In a diploid organism, one that has two copies of each chromosome, two alleles make up the individual's genotype. The word came from Greek αλληλος = "each other".
there are dominant and recessive

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heterozygous

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two different genes or alleles

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incomplete penetrance

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genes are dominant, but do not penetrate
therefore np phenotypic expression

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codominant

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this means both genes are expressed
example ABO Blood

Front 28

In almost all cells of the human body there are

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46 chromosomes-22 pairs oautosomes or somatic chromosomes and 2 sex chromosomes, XX or XY.

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Barr bodies

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inactive X chromosome in a female cell, or the inactive Z in a male

Front 30

karotype

Back 30

the simple arrangement of chromosomes by size.

Front 31

diploid number

Back 31

(2x) cells have two copies (homologs) of each chromosome, usually one from the mother and one from the father. The exact number of chromosomes may be one or two different from the 2x number yet the cell may still be classified as diploid (although with aneuploidy). Nearly all mammals are diploid organisms, although all individuals have some small fraction of cells that display polyploidy.

Front 32

euploid

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is the state of a cell or organism having an integral multiple of the monoploid number, possibly excluding the sex-determining chromosomes. For example, a human cell has 46 chromosomes, which is an integral multiple of the monoploid number, 23.

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aneuploidy

Back 33

Any deviation from euploidy (either up or down)

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polysomy

Back 34

An increase is
polysomy and the phenotype depends on which chromosome is extra. The most common
polysomy is Down's syndrome or trisomy (3) of chromosome 21.

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Nondysjunction

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the trisomies or monosomies develop because of the failure of
chromosomes to separate during cell division. XXY, or Klinefelters syndrome is another trisomy.

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monosomy

Back 36

A decrease in chromosome number is monosomy. Most are lethal except for Turners syndrome which is XO.

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XO Turner

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phenotype is an immature female with sterility. (Even though
one female X chromosome inactivates in the normal course of cellular maturation, it turns
out that 2 functional X chromosomes are necessary in utero for normal ovarian
development but not for the development of Mullerian structures, oviduct, uterus etc.)

Front 38

XXY-Klinefelters syndrome

Back 38

phenotype is immature male with sterility

Front 39

XYY

Back 39

about 2% of all males-initially thought to be a cause of excess aggression
but this concept is questionable.

Front 40

X-linked or sex-linked diseases.

Back 40

-Examples: Duchenne's muscular dystrophy, G6PDH deficiency, hemophilia, some forms
of color blindness.
-X-linked diseases characterized by affected males and normal females, but females are
the carriers. There is no male to male transmission.

Front 41

Autosomal Dominant Disorders

Back 41

Simply means that the dominant gene is on one of the 44 autosomes and since it is
dominant it will be expressed and produce an observable phenotype.
Examples-familial hypercholesterolemia (a dominant mutation in the gene
encloding for the LDL receptor); hereditary spherocytosis (a problem with red blood
cells).
-Although the genes for inherited genetic diseases are present from birth, the clinical or
biochemical phenotype may not be recognizable until later in life.
-Diseases in which the phenotype is present from birth are called congenital.
-Those becoming apparent later are called late onset or tarda.
Example are polycystic kidney disease and Huntington’s chorea
(HC). For HC penetrance is 80-90% by the 6th decade.

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Autosomal recessive.

Back 42

The syndrome or disease only manifests itself if 2 altered copies of an allele for the same
rotein-one from each parent- are present.
Ex: CF is an example. About 5% of Caucasians are heterozygotic; they have one
copy of the recessive abnormal gene and display no obvious phenotypic expression. Only
in the homozygous state is the clinical phenotype of CF present. As you recall CF is a
problem with the Cl channel (CFTR, cystic fibrosis transmembrane conductance
regulator) and affects the lungs and pancreas primarily. The CF gene in the heterozygotic
person may provide some protection against a number of infectious diseases including Cholera, Salmonella, P. aeruginosa. Other autosomal recessives include PKU and albinism. The former is caused by defective phenylalanine hydroxylase and the accumulation in the blood stream of a number of phenylalanine derivatives. The latter is caused by a defect in melanin biosynthesis, most often a result of an alteration or absence of the enzyme tyrosinase. Sickle cell anemia (SSA) is a more complex example of a genetic syndrome. It is often classified as an autosomal recessive disorder. In the homozygous state (about 0.1-0.2% of the African-American population) all Hb is HbS- the individual has inherited one copy of the altered gene from each parent. In the heterozygous state (about 9%), also called SS trait about 40% of Hb is HbS (the rest of the Hb is normal) and the tendency of these cells to sickle is much less. Cells that sickle provide a hostile environment for the organism that infects RBCs and causes malaria (plasmodium).

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balanced
polymorphism

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a selective advantage may be caltered allele result in a clear disease phenotype.The situations with CF and SSA are sometimes referred to as

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mitosis

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The process whereby cells divide and duplicate themselves

Front 45

p53

Back 45

Since
p53 has been implicated in about 50% of human cancers, a lot is known about it. It appears to have many functions and in this regard has been referred to as the guardian of
the genome. It may be involved in proof reading DNA or in initiating apoptosis if DNA is abnormal. p53 is activated by uv light (remember this is an energetic form of EM radiation like visible light but since it has higher energy can break chemical bonds, particularly susceptible is DNA).

Front 46

phases of mitosis

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prophase, metaphase, anaphase and telophase.

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chromatids

Back 47

Duplicated chromosomes

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cytokinesis

Back 48

During actual mitosis the 46 duplicated chromosomes line up in the midplane and separate. Separation of the chromosomes is followed by actual cell division

Front 49

Meiosis

Back 49

results in the production of sex cells or gametes, with a haploid (n) chromosome number.

Front 50

Gametogenesis

Back 50

The final products of meiosis participate in the process of sexual reproduction.
Gametogenesis occurs in the gonads (ovary in the female, testes in the male).

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During the second meiotic

Back 51

division the duplicated chromosomes are
now separated to give the n or haploid chromosome number. During meiosis several
significant events may occur. These include deletions, insertions, inversions, and
translocations.

Front 52

Example of meiosis --- sperm development

Back 52

Spermatogenesis and oogenesis. Stem cells called spermatogonia
divide by mitosis to produce primary spermatocytes. These undergo a first meiotic
division to form secondary spermatocytes. These in turn undergo the second meiotic
division to form spermatids having the n or haploid chromosome number. Spermatids
undergo further maturational changes to form a spermatozoan. Maturation occurs in the
epididymis and vas deferens where storage of sperm also occurs. In the male the process
of spermatogenesis is completed in the testes and related structures and results in the
production of 4 functional gametes from one primary spermatocyte. In the female,
meiosis results in the production of one functional gamete-the ovum- and the production
of several smaller cells referred to as polar bodies, which consist primarily of extraneous
nuclear material. The unequal distribution of cytoplasm is thought to ensure that if
fertilization occurs the zygote or fertilized ovum has the necessary cytoplasmic
constituents to survive

Front 53

Female reproduction

Back 53

In the female, the first meiotic division is completed several hours
prior to ovulation. The second meiotic division progresses to metaphase then stops. It
completes this phase when fertilization occurs. The fusion of the sperm and egg-
conception or fertilization or syngamy-results in the formation of a zygote with the 2n or
diploid chromosome number. The whole process of gametogregulated by FSH, LH, estrogens, progesterone, and testosterone