Cells and DNA

Question 1

What did people believe about offspring in the 19th century?

Answer 1

Offspring were the “average” of both their parents. This is called blending inheritance and this is false because this dilutes and eliminates variation and negates Darwin’s 2nd postulate

Question 2

What is the basic unit of life?

Answer 2

The cell. It is made of genetic material and other structures, complex life forms are made up of billions of cells

Question 3

What are prokaryotic cells?

Answer 3

They came before eukaryotes, single celled (bacteria, blue-green algae), and no nucleus around genetic material in cells

Question 4

What are eukaryotic cells?

Answer 4

Structurally complex cells, share a common ancestor with prokaryotes, and have a nucleus that has genetic information

Question 5

What are chromosomes?

Answer 5

Located in a cells nucleus, they are replicated in cell division are in homologous pairs in diploid organisms. An individual has 2 copies of each chromosomes (1 from mom and 1 from dad)

Question 6

What is mitosis?

Answer 6

It is normal cell division that aids in normal growth and maintenance of the body. It creates 2 exact copies of chromosomes pairs (diploid)

Question 7

What is meiosis?

Answer 7

Creates gametes (haploids), these haploid gametes pair up to become diploid and make a zygote

Question 8

What contains 2 complex molecules?

Answer 8

chromosomes contain proteins (histones) and nucleic acids (DNA)
- DNA carries hereditary information

Question 9

What are the characteristics of DNA?

Answer 9

2m long per chromosome, has a backbone of phosphate and sugar, inner links are base pairs, stable molecule that stores genetic information, cell machinery to ensure no mistakes are made
- 1 cell has 3 billion base pairs

Question 10

What are genes?

Answer 10

They are a unit of heredity. They are arranged on a chromosome and each gene is found in a specific location. Genes have alleles that are different forms of that gene (variation)

Question 11

What does DNA code for?

Answer 11

Some DNA codes for proteins, whilst others code for regulatory sequences

Question 12

What is a gene composed of?

Answer 12

Introns and exons

Question 13

What are protein coding genes?

Answer 13

DNA sequences that code for enzymes or non enzymatic proteins

Question 14

What are enzymes?

Answer 14

They catalyze/facilitate chemical reactions in cells (1 compound to another)

Question 15

What are non-enzymatic proteins?

Answer 15

Proteins that play a role in normal structure and function of cells (ex: hemoglobin, keratin)

Question 16

What do proteins consist of?

Answer 16

A chain of amino acids (primary structure) that can fold into 3d shapes (tertiary structure
- codons specify amino acids

Question 17

Can more than 1 combination code for an amino acid?

Answer 17

Yes. This is called redundant code or synonymous substitution.

Question 18

What is an exon?

Answer 18

A coding sequence that is spliced back together when introns are removed

Question 19

What is an intron?

Answer 19

A non-coding sequence that gets removed (important form of protein diversity)

Question 20

Can DNA sequences code for multiple proteins?

Answer 20

Yes

Question 21

What are the regulatory sequences?

Answer 21

They are encoded by DNA to determine if/when protein coding sequences are expressed. They are also binding sites for repressor and activator proteins
- Large source of phenotypic variation

Question 22

Where are the regulatory sequences located?

Answer 22

They are located near the protein coding sequence

Question 23

Why isn’t all DNA expressed?

Answer 23

All cells have your genetic library, but if all DNA was expressed then all the cells would be the same

Question 24

What does gene regulation allow?

Answer 24

It allows for diffrentiation, so for a single cell to grow into a zygote. It creates variation in cells (ex: they can turn into heart cells, bone cells, etc..)

Question 25

What is point mutation?

Answer 25

It is a change in a single DNA base

Question 26

What is recombination?

Answer 26

New combinations of alleles (crossing over), which is important for variation