EOCT Review (Genetics)

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14 Δεκ 2012 (πριν από 4 χρόνια και 8 μήνες)

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Domain III
-

Genetics


Deoxyribonucleic acid


Made up of
nucleotides


Sugar


deoxyribose


A phosphate group


One of four nitrogen bases


Adenine (A)


Guanine (G)


Cytosine (C)


Thymine (T)


Is in the shape of a
double helix


The two strands are
held together by
hydrogen bonds
between the
nucleotides


Adenine pairs with
thymine


Guanine pairs with
cytosine


The order of the
bases is the genetic
code


DNA makes an exact copy of itself


Takes place in the
nucleus

1.
An enzyme ‘unzips’ the DNA

2.
Free nucleotides pair up with the
exposed nucleotides

3.
This continues until two identical
copies of the DNA molecule are made


The two copies each contain one
side from the ‘original’ DNA and one
‘new’ side


Ribonucleic acid


3 differences (from DNA):


Sugar is
ribose

instead of
deoxyribose


Uracil

instead of thymine


Single helix

instead of a double helix


3 types of RNA:


Messenger RNA (mRNA)


Transfer RNA (
tRNA
)


Ribosomal RNA (
rRNA
)


The process of
making RNA from
DNA


Occurs in the
nucleus


Only one side of
the DNA strand is
used to make the
RNA



The process of converting the
information on the mRNA into a protein


The mRNA carries the message from
the nucleus to the
ribosomes
, where
the proteins are made


The
tRNA

molecules bring the amino
acids to the
ribosomes


The 3 base
codon

on the mRNA corresponds
to a 3 base
anticodon

on the
tRNA


Each
codon

carries the code for a specific
amino acid


Which of the following shows how
information is transformed to make
a protein?

a.
DNA

RNA

protein

b.
gene

chromosome

protein

c.
cell respiration

ATP

protein

d.
ATP

amino acid

protein


Information on mRNA is used to
make a sequence of amino acids
into a protein by which of the
following processes?

a.
replication

b.
translation

c.
transcription

d.
transference


‘Father of Genetics’


Studied inheritance in pea plants


Concluded that each organism has
two genes for each trait


one from
mom, one from dad


Genes come in different forms
called
alleles


Dominant



the trait that is expressed


Recessive



the trait that is hidden


Law of Dominance



the dominant
allele will prevent the recessive allele
from being expressed


Law of Segregation



gene pairs
separate when gametes are formed, so
each gamete has only one allele of
each pair


Law of Independent Assortment



different pairs of genes separate
independently of each other when
gametes are formed


Homozygous



two identical alleles (TT or
tt
)


Heterozygous



two different alleles (
Tt
)


Monohybrid



genetic cross involving one
trait


Dihybrid



genetic cross involving two traits


Genotype



the genetic makeup of the
organism (
Tt
)


Phenotype



the physical appearance of
the trait (tall)


Pea plants have seeds that are
either round or wrinkled. In this
cross, what will be the phenotypic
ratio of the offspring?

a.
50% RR and 50%
Rr

b.
25% RR, 50%
Rr
, and
25%
rr

c.
50% round seeds and
50% wrinkled seeds

d.
100% round seeds


Interphase


G1 phase


cell
growth


S phase


DNA
replication


G2 phase


preparation for
mitosis


M phase


Mitosis


Cytokinesis



division
of the cytoplasm


Division of the nucleus


Two identical daughter cells are
produced


The chromosome number remains
the same


Purpose:


Growth and tissue repair


Asexual reproduction


Prophase



the duplicated chromosomes
become visible and spindle fibers form
across the cell; the nuclear envelope starts
to break up


Metaphase



the chromosomes attach to
the spindle and line up randomly in the
middle of the cell


Anaphase



the chromosomes are pulled to
opposite ends of the cell


Telophase



a nuclear membrane forms
around the chromosomes at each end of
the cell; spindle fibers disappear;
chromosomes become less visible


Why is it important for the cells of
multicellular

organisms to undergo
mitosis?

a.
Mitosis allows for reproduction with male
and female gametes.

b.
Mitosis increases variation within an
organism.

c.
Mitosis produces cells that are different
from the original dividing cell.

d.
Mitosis produces identical cells to the
original dividing cell.


The production of gametes (sex cells


sperm and eggs)


The chromosome number is cut in
half, producing haploid gametes


Diploid (2n)



2 of each chromosome


Normal body cells


Haploid (n)



1 of each chromosome


Sex cells


There are two divisions


Meiosis I


Prophase I


crossing over can occur


Metaphase I


Anaphase I


Telophase

I


Meiosis II


Prophase II


Metaphase II


Anaphase II


Telophase

II


Changes in the nucleotide sequence
of a DNA molecule


Substitution


a single nucleotide is
substituted for another one (A
instead of G)


Insertion


a nucleotide is added


Deletion


a nucleotide is removed


A mutation can be harmful, neutral,
or beneficial depending on how it
affects the protein that is produced


What is a source of genetic
variation?

a.
mutation

b.
adaptation

c.
replication

d.
transcription


Recombinant DNA


inserting foreign
genes


Human insulin is mass produced by bacteria
that have had the human insulin gene
inserted


Creates genetically modified organisms


Cotton plants have been modified to resist
worm attacks


Bacteria have been modified to clean up oil
spills, manufacture alcohol, and process
minerals


Which of the following is the
correct base
-
pairing rule for DNA?

a.
A
-
U; C
-
G

b.
A
-
G; T
-
C

c.
A
-
T; G
-
C

d.
A
-
C; T
-
G


A mutagenic factor that can alter
DNA by the loss of a chromosome
segment is known as

a.
translocation

b.
crossing over

c.
deletion

d.
nondisjunction


In Mendel’s experiments with a
single trait, the trait that
disappeared in the first generation
and reappeared in the next
generation is called the

a.
homozygous trait

b.
dominant trait

c.
recessive trait

d.
heterozygous trait


Which of the
following
correctly shows
the shape of a
DNA molecule?


Changes to an organism’s DNA can
cause unexpected traits to be
expressed in its offspring. DNA in
an individual’s gametes will most
likely be altered before being
passed to offspring if exposed to

a.
x
-
rays

b.
loud sounds

c.
magnetic fields

d.
extreme temperatures


Agricultural companies have
developed the ability to control the
genetic characteristics of their crops.
Genetic engineering techniques have
been used to produce all of the
following effects except

a.
grow salt
-
tolerant crop plants

b.
decrease harvesting time

c.
make crop plants resistant to disease

d.
decrease soil nitrogen levels


In fruit flies, the gray body color
(G) is dominant to the ebony body
color (g). What is the genotypic
ratio of the offspring of a
heterozygous gray female and an
ebony male?

a.
25%
Gg
, 75%
gg

b.
50%
Gg
, 50%
gg

c.
75% gray, 25% ebony

d.
100% gray


The process of meiosis produces
gametes. How does this process
increase reproductive variability?

a.
Different combinations of alleles are
produced.

b.
Each allele from the parent cell forms
a separate gamete.

c.
Each pair of genes undergoes crossing
-
over with different genes.

d.
The two genes are passed on to a
daughter cell, resulting in new traits.


DNA and RNA are nucleic acids. A
characteristic of RNA is that it

a.
remains in the chromosomes in the
nucleus

b.
is involved in translating information
in DNA into proteins

c.
undergoes crossing
-
over during meiosis

d.
is replicated during the process of
mitosis


ATG is a DNA triplet that codes for
an amino acid. Which mRNA
codon

will pair with the ATG triplet

a.
ATG

b.
GTU

c.
TAC

d.
UAC

1.
A

2.
B

3.
D

4.
D

5.
A

6.
C

7.
C

8.
C

9.
D

10.
A

11.
D

12.
B

13.
A

14.
B

15.
D




http://www.doe.k12.ga.us/ci_testin
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Google image search


Campbell, Neil A. and Reece Jane B
(2001). "6".
Biology
. Benjamin
Cummings.


Miller, Kenneth R. and Levine Joseph
S. (2002).
Biology
. Prentice Hall.