Cells And Genes

Question 1

What are the organelles of an animal cell?

Answer 1

Nucleolus
Nucleus
Ribosome
Vesicle
RER
Golgi apparatus 
Cytoskeleton
SER
Mitochondria
Vacuole
Cytoplasm
Lysosome
Centriole

Question 2

What organelle do cells with high energy requirements e.g. muscle and liver cells have a lot of?

Answer 2

Mitochondria

Question 3

What organelle do cells that secrete protein e.g. pancreatic cells, have a lot of?

Answer 3

RER

Golgi apparatus

Question 4

What are the stages of the cell cycle?

Answer 4

G0: resting/quiescent
G1 (cells can enter here from M or G0)
S phase: DNA replication
G2
M: nuclear + cytoplasmic division (mitosis)

Question 5

What are chromosomes?

Answer 5

Structures that contain our genetic material that are made of chromatin (DNA + histones that package + condense the DNA)

Question 6

Explain the phases of mitosis.

Answer 6

1. Interphase (G2): cell at rest
2. Prophase: nuclear membrane breaking down, chromosomes condensing + centrosomes migrating to opposite poles of cell producing spindle fibres
3. Prometaphase: nucleus dissolved, centrosomes at poles, chromosomes attach to spindle fibres along with kinetochore
4. Metaphase: all chromosomes lined up in middle attached to spindle fibres with all kinetochores
5. Anaphase: sister chromatids pulled apart
6. Telophase: reestablishment of nuclei containing genetic material + cytoplasm starting to split at cleavage furrow
7. Interphase (G1): 2 cells made

Question 7

What are cellular adaptations?

Answer 7

Reversible changes in cells in response to changes in the environment as a result of physiological or pathological conditions

Question 8

What changes can cells undertake when adapting?

Answer 8

Number
Size
Cell type

Question 9

The way that cells adapt depends partly on:

Answer 9

Their ability to divide

Question 10

Define hyperplasia.

Answer 10

Increase in no. of cells in a tissue (cells must be able to divide to do this)

Question 11

Define hypertrophy.

Answer 11

Increase in cell size involving an increase n cellular contents as well as swelling (all cells)

Question 12

Define atrophy.

Answer 12

Reduction in cell size involving internal digestion of cellular contents (autophagy)

Question 13

Define metaplasia.

Answer 13

Reversible change from one cell type to another (usually in epithelia; can develop into cancer)

Question 14

Why is genetics important?

Answer 14

Humans have ~20,000 genes encoding RNA + protein with diverse biochemical functions; many gene products regulate other genes

Genes contribute to every biological feature in healthy + diseased states (many have profound effects during embryonic development)

Question 15

___ people under the age of 25 will develop a disease with a significant genetic component.

Answer 15

1 in 20

Question 16

What is the genome?

Answer 16

Complete haploid set of genetic material in an organism (3x10^9 DNA base pairs in humans)

Question 17

What is a karyotype?

Answer 17

Humans normally have 23 pairs of chromosomes:

• 22 pairs of autosomes
• 1 pair of sex chromosomes (XX = females, XY = males)

Question 18

What are genes?

Answer 18

Segments of DNA within the genome that encode RNA + usually protein which make up our genotype

Question 19

What is a Punnett square?

Answer 19

Simple grid used to draw expected outcomes of matings; it can be used to predict the probability that a new individual will have a particular genotype

Question 20

How are Punnett squares used?

Answer 20

Genotype of 1 parent written along top of square

Genotype of other parent written down side of square

= 4 possible genotypes resulting from mating are drawn in grid

Question 21

What factors make up a persons phenotype?

Answer 21

Anatomy, physiology + psychology

Which can be influenced by GENOTYPE + ENVIRONMENT (changes over time due to environmental factors)

Question 22

What does it mean to be genetically susceptible to a disease?

Answer 22

It does not mean a person will necessarily develop the disease but is at an increased risk

Question 23

What are alleles?

Answer 23

If different versions of a gene exist in a population, the gene is polymorphic + different versions are called alleles

Question 24

What is a wild type gene?

Answer 24

Allele that is most common in a population usually not associated with disease

Question 25

What is the difference between homozygous and heterozygous chromosomes?

Answer 25

Chromosomes are arranged in pairs so there are 2 copies of each gene in an individual; they can either be identical (homozygous) or different (heterozygous)

Question 26

What so dominant, co-dominant and recessive alleles do?

Answer 26

Dominant alleles determine phenotype over recessive alleles whereas co-dominant alleles jointly determine phenotype

Question 27

Give an example of dominance and co-dominance.

Answer 27

ABO blood grouping:

• A + B alleles co-dominant with respect to eachother
• A + B alleles dominant with regard to O allele
• O allele recessive with respect to A + B alleles

Question 28

Using a Punnett square, work out the potential outcomes of the offspring if both parents are AB blood group.

Answer 28

A B
A AA AB
B AB BB

Offspring will either be A (25%), AB (50%) or B (25%)

Question 29

How are genes, proteins + phenotype related?

Answer 29

Genes related to phenotype via genetics

Genes related to proteins via molecular biology

Proteins related to phenotype via biochemistry

Phenotype = function