DNA Deoxyribonucleic acid Made up of nucleotides
Sugar – deoxyriboseA phosphate groupOne of four nitrogen bases
Adenine (A) Guanine (G) Cytosine (C) Thymine (T)
Is in the shape of a double helix
DNA 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 REPLICATION DNA makes an exact copy of itself Takes place in the nucleus
1. An enzyme ‘unzips’ the DNA2. Free nucleotides pair up with the
exposed nucleotides3. 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
RNA Ribonucleic acid 3 differences (from DNA):
Sugar is ribose instead of deoxyribose
Uracil instead of thymineSingle helix instead of a double
helix 3 types of RNA:
Messenger RNA (mRNA)Transfer RNA (tRNA)Ribosomal RNA (rRNA)
TRANSCRIPTION The process of
making RNA from DNA
Occurs in the nucleus
Only one side of the DNA strand is used to make the RNA
TRANSLATION 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 ribosomesThe 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
QUESTION #1 Which of the following shows how information is transformed to make a protein?a. DNA → RNA → proteinb. gene → chromosome → proteinc. cell respiration → ATP → proteind. ATP → amino acid → protein
QUESTION #2 Information on mRNA is used to make a sequence of amino acids into a protein by which of the following processes?a. replicationb. translationc. transcriptiond. transference
GREGOR MENDEL ‘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 allelesDominant – the trait that is
expressedRecessive – the trait that is hidden
MENDEL’S LAWS 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
GENETICS VOCABULARY 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)
QUESTION #3 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% Rrb. 25% RR, 50% Rr, and
25% rrc. 50% round seeds and
50% wrinkled seedsd. 100% round seeds
THE CELL CYCLE Interphase
G1 phase – cell growth
S phase – DNA replication
G2 phase – preparation for mitosis
M phase Mitosis Cytokinesis –
division of the cytoplasm
MITOSIS Division of the nucleus Two identical daughter cells are
produced The chromosome number
remains the same Purpose:
Growth and tissue repairAsexual reproduction
PHASES OF MITOSIS 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
QUESTION #4 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.
MEIOSIS The production of gametes (sex
cells – sperm and eggs) The chromosome number is cut
in half, producing haploid gametesDiploid (2n) – 2 of each
chromosome Normal body cells
Haploid (n) – 1 of each chromosome Sex cells
MEIOSIS 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
GENE MUTATIONS Changes in the nucleotide
sequence of a DNA moleculeSubstitution – a single nucleotide is substituted for another one (A instead of G)
Insertion – a nucleotide is addedDeletion – a nucleotide is removed
A mutation can be harmful, neutral, or beneficial depending on how it affects the protein that is produced
QUESTION #5 What is a source of genetic variation?a. mutationb. adaptationc. replicationd. transcription
GENETIC ENGINEERING Recombinant DNA – inserting foreign
genesHuman 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 attacksBacteria have been modified to clean up
oil spills, manufacture alcohol, and process minerals
QUESTION #6 Which of the following is the correct base-pairing rule for DNA?a. A-U; C-Gb. A-G; T-Cc. A-T; G-Cd. A-C; T-G
QUESTION #7 A mutagenic factor that can alter DNA by the loss of a chromosome segment is known asa. translocationb. crossing overc. deletiond. nondisjunction
QUESTION #8 In Mendel’s experiments with a single trait, the trait that disappeared in the first generation and reappeared in the next generation is called thea. homozygous traitb. dominant traitc. recessive traitd. heterozygous trait
QUESTION #10 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 toa. x-raysb. loud soundsc. magnetic fieldsd. extreme temperatures
QUESTION #11 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 excepta. grow salt-tolerant crop plantsb. decrease harvesting timec. make crop plants resistant to diseased. decrease soil nitrogen levels
QUESTION #12 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% ggb. 50% Gg, 50% ggc. 75% gray, 25% ebonyd. 100% gray
QUESTION #13 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.
QUESTION #14 DNA and RNA are nucleic acids. A characteristic of RNA is that ita. remains in the chromosomes in
the nucleusb. is involved in translating
information in DNA into proteinsc. undergoes crossing-over during
meiosisd. is replicated during the process of
mitosis
QUESTION #15 ATG is a DNA triplet that codes for an amino acid. Which mRNA codon will pair with the ATG tripleta. ATGb. GTUc. TACd. UAC
INFORMATION AND IMAGES OBTAINED FROM: http://www.doe.k12.ga.us/ci_test
ing.aspx?PageReq=CI_TESTING_EOCT&SubPageReq=GUIDES
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.
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