Lactose Lab Quiz Monday 5/19

Question 1

Lactase

Answer 1

an enzyme that breaks down lactose (milk sugar) into glucose and galactose so your body can absorb it

Question 2

What happens without lactase?

Answer 2

Without lactase, lactose ferments in the large intestine → gas, bloating, diarrhea.

Question 3

What is an indicator of lactase activity?

Answer 3

Presence of glucose = lactase activity.

Question 4

Enzyme

Answer 4

A type of protein that speeds up chemical reactions without being used up. Enzymes are very specific in what they act on

Question 5

Enzymes are not shape-specific

True or False

Answer 5

False

Enzymes are shape-specific. This means that an enzyme only binds certain molecules that have the right shape

Question 6

Enzyme activity can be measured with-

Answer 6

glucose test strips

Question 7

What codes lactase?

Answer 7

LCT gene codes for lactase.

Question 8

The lactase gene is normally turned on in adults

True or False

Answer 8

False

Normally turned off in adults (ancestral condition).

Question 9

What keeps LCT active into adulthood for some people?

Answer 9

Some people have a mutation in the control region that keeps LCT active into adulthood.

Question 10

Coding regions:

Answer 10

The part of a gene that actually codes for the amino acid sequence of a protein

Question 11

Noncoding (control) regions:

Answer 11

The part of DNA that doesn’t make proteins but controls whether a gene is turned on or off

Question 12

Silent mutation:

Answer 12

A DNA change that doesn’t affect the protein being made—usually because the amino acid stays the same

Question 13

Alleles L&l:

Answer 13

L: dominant, lactase produced

l: recessive, no lactase

Question 14

What can increase L frequency over generations?

Answer 14

Environmental pressure (e.g., reliance on milk) can increase L frequency over generations

Question 15

Lactose

Answer 15

A sugar found in milk. It is made of two smaller sugars: glucose and galactose

Question 16

Substrate

Answer 16

The substance that an enzyme acts on. In this lab, the substrate is lactose

Question 17

Glucose

Answer 17

A simple sugar your body uses for energy. Its presence after lactase acts on milk shows lactose was broken down

Question 18

Gene

Answer 18

A section of DNA that has the instructions to make a specific protein

Question 19

LCT gene

Answer 19

The gene that gives the instructions for making lactase. It is found on chromosome 2

Question 20

Mutation

Answer 20

A change in the DNA sequence. Some mutations can affect traits, while others (like silent mutations) don’t change the protein

Question 21

DNA

Answer 21

The molecule that holds genetic information. It’s made of bases (A, T, C, G) and is found in the nucleus of cells

Question 22

mRNA (messenger RNA)

Answer 22

A copy of a gene that is made from DNA and used to build proteins in the cell

Question 23

Amino acids

Answer 23

The building blocks of proteins. The sequence of amino acids determines the shape and function of the protein

Question 24

Protein

Answer 24

A molecule made of amino acids that performs many jobs in the body, like enzymes, hormones, and structural parts

Question 25

Denature

Answer 25

When an enzyme loses its shape due to heat or pH changes and no longer works properly

Question 26

Homeostasis

Answer 26

The body’s way of keeping things stable and balanced, like keeping blood sugar levels normal

Question 27

Allele

Answer 27

A version of a gene. You inherit one from each parent. In this lab: L = lactose tolerant l = lactose intolerant

Question 28

Genotype

Answer 28

The combination of alleles an individual has (e.g., LL, Ll, or ll)

Question 29

Phenotype

Answer 29

The physical trait you see based on the genotype (e.g., being lactose tolerant or intolerant)

Question 30

Natural selection

Answer 30

The process where traits that help survival become more common in a population over time

Question 31

Environmental pressure

Answer 31

A factor (like relying on milk) that makes some traits more helpful, leading to natural selection

Question 32

Selective advantage

Answer 32

A trait that gives an organism a better chance to survive and reproduce

Question 33

Diffusion

Answer 33

Movement of molecules (like glucose) from an area of high concentration to low concentration. Glucose diffuses from the intestine to the blood

Question 34

Simulation

Answer 34

A model or activity that represents a real-life process, like inheritance or evolution

Question 35

How might epigenetic changes like methylation influence gene expression?

Answer 35

modifying the structure of DNA and how it interacts with other molecules