Cells and DNA

Question 1

BLENDING INHERITANCE

Answer 1

Darwin’s idea that offspring would be an “average” of their parents (not correct)

Question 2

ISSUE WITH BLENDING INHERITANCE

Answer 2

• cannot explain how variation persists across generations
• dilutes and eventually eliminates variation
• traits would continuously blend and average out, eventually leading to a population with uniform characteristics, making natural selection impossible

Question 3

THE CELL

Answer 3

Basic unit of life (comprised of genetic material)

Question 4

PROKARYOTIC CELLS

Answer 4

Single-celled organisms without a nucleus.

Question 5

EUKRAYOTIC CELLS

Answer 5

Complex cells with a nucleus and organelles.

Question 6

CHROMOSONES

Answer 6

• Small linear bodies contained in every cell
• Replicated during cell division
• Exist in homologous pairs in diploid organisms

Question 7

CELL DIVISON: MITOSIS

Answer 7

The division of cells in which two exact copies of chromosome pairs are made (diploid)

Question 8

CELL DIVISON: MEIOSIS

Answer 8

Cell division creating haploid gametes for reproduction

Question 9

FERTILIZATION

Answer 9

The process in which haploid sperm join haploid ovum to produce a zygote. (zygote is diploid)

Question 10

DNA

Answer 10

• Double helix of nucleotides with phosphate-sugar backbone
• Stores information
• The chemical basis of hereditary
• Responsible for the genetic makeup of an individual
• Adenine (A) only bonds with Thymine (T)
• Cytosine (C) only bonds with Guanine (G)
• “Alphabet” with four repeating letters in infinite combinations

Question 11

DIFFERENCES IN DNA SEQUENCE LEAD TO VARTIATION THROUGH TWO WAYS:

Answer 11

1) Some DNA codes for proteins

2) Some DNA codes for regulatory sequences

Question 12

GENE

Answer 12

• Segment of DNA that makes a functional product
• Unit of hereditary, specifies traits
• Arranged on chromosomes “like beads on a string”
• Each gene found at a specific point on the chromosome (locus)
• Segregates as a unit during gamete formation

Question 13

PROTEIN-CODING GENES

Answer 13

DNA sequences code for two main types of protein:

• Enzymes
• Non-enzymatic proteins

Question 14

ENZYMES

Answer 14

Proteins that catalyze chemical reactions in cells

Question 15

EXONS

Answer 15

• Coding sequences in genes, spliced together
• Covalently bonded to one another to create mature mRNA

Question 15

INTRONS

Answer 15

• Non-coding sequences removed during RNA processing
• Intros are removed by RNA splicing as RNA matures, meaning that they are not expressed in the final messenger RNA (mRNA)

Question 15

REGULATAORY SEQUNCES

Answer 15

DNA segments controlling gene expression timing

Question 15

MUTATIONS

Answer 15

• Changes in DNA sequence
• Can cause a change in chromosome # / structure
• Not always negative, source of variation

Question 15

POINT MUTATION

Answer 15

Change in a single DNA base

Question 16

RECOMBINATIONS

Answer 16

• New combinations of alleles
• Created through the breaking and rejoining of DNA strands in a new order
• Source of variation

Question 17

HOMOZYGOUS

Answer 17

The individual carries two identical alleles for a given gene

Question 18

HETEROZYGOUS

Answer 18

The individual carries two different alleles for a given gene

Question 19

DOMINANT TRAIT

Answer 19

An allele that suppresses other alleles

Question 20

RECESSIVE TRAIT

Answer 20

An allele whose expression is suppressed by dominant forms

No effect on phenotypes in heterozygotes

Question 21

GENOTYPE

Answer 21

Refers to the particular combination of genes or alleles that an individual carries (e.g. AA, Aa, aa)

Question 22

PHENOTYPE

Answer 22

Refers to the observable characteristics of the organism, such as the colour of the peas in Mendel's experiments